diff --git a/geneve/constraints.py b/geneve/constraints.py
index 7db90647..d88e8651 100644
--- a/geneve/constraints.py
+++ b/geneve/constraints.py
@@ -128,7 +128,11 @@ def _solver(cls, field, value, constraints):
                         if len(v) > 1:
                             raise ValueError(f"Too many arguments for cardinality of '{field}': {v}")
                         v = v[0]
-                    cardinality = int(v)
+                    v = int(v)
+                    if not cardinality or cardinality == v:
+                        cardinality = v
+                    else:
+                        raise ConflictError(f"is already {cardinality}, cannot set to {v}", field, k)
                     history = cls.fields_history.setdefault(field, [])
             if max_attempts is None:
                 max_attempts = _max_attempts
diff --git a/geneve/events_emitter_eql.py b/geneve/events_emitter_eql.py
index 6bbace36..9eef6483 100644
--- a/geneve/events_emitter_eql.py
+++ b/geneve/events_emitter_eql.py
@@ -171,8 +171,10 @@ def cc_join_branch(seq: List[Tuple[Constraints, List[str]]]) -> Branch:
     for join_col in zip(*join_rows):
         field0 = None
         for field, c in join_col:
-            field0 = field0 or field
-            constraints[0].append_constraint(field0, "join_value", (field, c))
+            if field0 is None:
+                field0 = field
+            else:
+                constraints[0].append_constraint(field0, "join_value", (field, c))
     return Branch(constraints)
 
 
diff --git a/tests/reports/documents_from_queries.ipynb b/tests/reports/documents_from_queries.ipynb
index c28da049..97a207d7 100644
--- a/tests/reports/documents_from_queries.ipynb
+++ b/tests/reports/documents_from_queries.ipynb
@@ -2092,16 +2092,50 @@
    ]
   },
   {
-   "cell_type": "markdown",
+   "cell_type": "code",
+   "execution_count": null,
    "id": "3c7a3d01",
    "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[[{'event': {'category': ['network']}, 'destination': {'ip': '1::f09b', 'port': 265}},\n",
+       "  {'event': {'category': ['network']}, 'source': {'ip': '1::f09b', 'port': 265}, 'destination': {'ip': '1::1cf0', 'port': 22623}}],\n",
+       " [{'event': {'category': ['network']}, 'destination': {'ip': '1::f09b', 'port': 691}},\n",
+       "  {'event': {'category': ['network']}, 'source': {'ip': '1::f09b', 'port': 691}, 'destination': {'ip': '1::1cf0', 'port': 57576}}],\n",
+       " [{'event': {'category': ['network']}, 'destination': {'ip': '1::f09b', 'port': 173}},\n",
+       "  {'event': {'category': ['network']}, 'source': {'ip': '1::f09b', 'port': 173}, 'destination': {'ip': '1::1cf0', 'port': 3897}}],\n",
+       " [{'event': {'category': ['network']}, 'destination': {'ip': '1::f09b', 'port': 685}},\n",
+       "  {'event': {'category': ['network']}, 'source': {'ip': '1::f09b', 'port': 685}, 'destination': {'ip': '1::f09b', 'port': 58442}}],\n",
+       " [{'event': {'category': ['network']}, 'destination': {'ip': '1::f09b', 'port': 929}},\n",
+       "  {'event': {'category': ['network']}, 'source': {'ip': '1::f09b', 'port': 929}, 'destination': {'ip': '1::1cf0', 'port': 54423}}]]"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "emit('''\n",
+    "    sequence\n",
+    "            [network where _cardinality(destination.ip, 1) and destination.port < 1024] by destination.ip, destination.port\n",
+    "            [network where _cardinality(destination.ip, 2) and destination.port > 1024] by source.ip, source.port\n",
+    "''', count=5)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "5090731a",
+   "metadata": {},
    "source": [
     "## Any oddities?"
    ]
   },
   {
    "cell_type": "markdown",
-   "id": "5090731a",
+   "id": "c3fb7b7a",
    "metadata": {},
    "source": [
     "Did you find anything odd reviewing the report or playing with the documents emitter?\n",
diff --git a/tests/test_constraints.py b/tests/test_constraints.py
index bab6ad37..098acdba 100644
--- a/tests/test_constraints.py
+++ b/tests/test_constraints.py
@@ -950,6 +950,13 @@
         ],
         """Too many arguments for cardinality of 'test_var': (0, 1)""",
     ),
+    (
+        [
+            ("cardinality", 1),
+            ("cardinality", 0),
+        ],
+        "Unsolvable constraints cardinality: test_var (is already 1, cannot set to 0)",
+    ),
 ]
 
 
diff --git a/tests/test_emitter_queries.py b/tests/test_emitter_queries.py
index 8fe046d0..6fdc46b4 100644
--- a/tests/test_emitter_queries.py
+++ b/tests/test_emitter_queries.py
@@ -557,6 +557,55 @@
             [{"event": {"category": ["network"]}, "destination": {"ip": "1::f14", "port": 443}}],
         ],
     ),
+    (
+        """sequence
+            [network where _cardinality(destination.ip, 1) and destination.port < 1024] by destination.ip, destination.port
+            [network where _cardinality(destination.ip, 2) and destination.port > 1024] by source.ip, source.port
+        """,
+        1,
+        [
+            [
+                {"event": {"category": ["network"]}, "destination": {"ip": "1::f09b", "port": 265}},
+                {
+                    "event": {"category": ["network"]},
+                    "source": {"ip": "1::f09b", "port": 265},
+                    "destination": {"ip": "1::1cf0", "port": 22623},
+                },
+            ],
+            [
+                {"event": {"category": ["network"]}, "destination": {"ip": "1::f09b", "port": 691}},
+                {
+                    "event": {"category": ["network"]},
+                    "source": {"ip": "1::f09b", "port": 691},
+                    "destination": {"ip": "1::1cf0", "port": 57576},
+                },
+            ],
+            [
+                {"event": {"category": ["network"]}, "destination": {"ip": "1::f09b", "port": 173}},
+                {
+                    "event": {"category": ["network"]},
+                    "source": {"ip": "1::f09b", "port": 173},
+                    "destination": {"ip": "1::1cf0", "port": 3897},
+                },
+            ],
+            [
+                {"event": {"category": ["network"]}, "destination": {"ip": "1::f09b", "port": 685}},
+                {
+                    "event": {"category": ["network"]},
+                    "source": {"ip": "1::f09b", "port": 685},
+                    "destination": {"ip": "1::f09b", "port": 58442},
+                },
+            ],
+            [
+                {"event": {"category": ["network"]}, "destination": {"ip": "1::f09b", "port": 929}},
+                {
+                    "event": {"category": ["network"]},
+                    "source": {"ip": "1::f09b", "port": 929},
+                    "destination": {"ip": "1::1cf0", "port": 54423},
+                },
+            ],
+        ],
+    ),
 ]