diff --git a/msccl/language/instruction_dag.py b/msccl/language/instruction_dag.py
index 7bd70bf..d099126 100755
--- a/msccl/language/instruction_dag.py
+++ b/msccl/language/instruction_dag.py
@@ -19,6 +19,9 @@ def remove_op(op: Op):
 
 
 def merge_op(op: Op, other_op: Op):
+    if other_op in op.next:
+        op.next.remove(other_op)
+        other_op.prev.remove(op)
     for p in other_op.prev:
         p.next.remove(other_op)
         p.next.append(op)
@@ -28,7 +31,7 @@ def merge_op(op: Op, other_op: Op):
         n.prev.add(op)
 
     op.prev = op.prev.union(other_op.prev)
-    op.next += other_op.next
+    op.next = list(set(op.next + other_op.next))
 
 
 def same_tb(op1: Op, op2: Op):
diff --git a/msccl/language/mscclpp/instruction_dag.py b/msccl/language/mscclpp/instruction_dag.py
index 28dcd8b..32d15b1 100644
--- a/msccl/language/mscclpp/instruction_dag.py
+++ b/msccl/language/mscclpp/instruction_dag.py
@@ -243,7 +243,7 @@ def _optimize_rrc_r_signal_wait(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True
@@ -266,7 +266,7 @@ def _optimize_rrc_r_signal_wait(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True
@@ -289,7 +289,7 @@ def _optimize_rrc_r_signal_wait(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True
@@ -320,7 +320,7 @@ def _optimize_rrc_r_signal_wait(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True
@@ -351,7 +351,7 @@ def _optimize_rrc_r_signal_wait(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True
@@ -389,7 +389,7 @@ def _optimize_rrcs_rs(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True
@@ -418,7 +418,7 @@ def _optimize_rrcs_rs(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True
@@ -447,7 +447,7 @@ def _optimize_rrcs_rs(self):
                                         next_op.step,
                                     )
                                 )
-                                remove_op(next_op)
+                                merge_op(op, next_op)
                                 tb.ops.remove(next_op)
                                 queue.remove(next_op)
                                 fused = True