diff --git a/rvfi/checks/unique_check.py b/rvfi/checks/unique_check.py
new file mode 100644
index 0000000..ae785f4
--- /dev/null
+++ b/rvfi/checks/unique_check.py
@@ -0,0 +1,43 @@
+from nmigen import *
+from nmigen.asserts import *
+
+"""
+Unique Check
+"""
+
+class UniqueCheck(Elaboratable):
+    def __init__(self):
+        self.reset = Signal(1)
+        self.rvfi_valid = Signal(1)
+        self.rvfi_order = Signal(64)
+        self.trig = Signal(1)
+        self.check = Signal(1)
+
+    def ports(self):
+        input_ports = [
+            self.reset,
+            self.rvfi_valid,
+            self.rvfi_order,
+            self.trig,
+            self.check
+        ]
+        return input_ports
+
+    def elaborate(self, platform):
+        m = Module()
+
+        insn_order = AnyConst(64)
+        found_other_insn = Signal(1, reset=0)
+
+        with m.If(self.reset):
+            m.d.sync += found_other_insn.eq(0)
+        with m.Else():
+            with m.If(self.rvfi_valid & (self.rvfi_order == insn_order) & ~self.trig):
+                m.d.sync += found_other_insn.eq(1)
+            with m.If(self.trig):
+                m.d.comb += Assume(self.rvfi_valid)
+                m.d.comb += Assume(insn_order == self.rvfi_order)
+            with m.If(self.check):
+                m.d.comb += Assert(~found_other_insn)
+
+        return m
diff --git a/rvfi/cores/minerva/verify.py b/rvfi/cores/minerva/verify.py
index 8bc3b8b..e9f0b95 100644
--- a/rvfi/cores/minerva/verify.py
+++ b/rvfi/cores/minerva/verify.py
@@ -5,6 +5,7 @@ from ...checks.pc_bwd_check import *
 from ...checks.reg_check import *
 from ...checks.causal_check import *
 from ...checks.liveness_check import *
+from ...checks.unique_check import *
 from minerva.core import *
 from ...insns.insn_lui import *
 from ...insns.insn_auipc import *
@@ -241,6 +242,25 @@ class LivenessTestCase(FHDLTestCase):
     def verify(self):
         self.assertFormal(LivenessSpec(), mode="bmc", depth=12, engine="smtbmc --nopresat")
 
+class UniqueSpec(Elaboratable):
+    def elaborate(self, platform):
+        m = Module()
+
+        m.submodules.cpu = cpu = Minerva(with_rvfi=True)
+        m.submodules.unique_spec = unique_spec = UniqueCheck()
+
+        m.d.comb += unique_spec.reset.eq(0)
+        m.d.comb += unique_spec.rvfi_valid.eq(cpu.rvfi.valid)
+        m.d.comb += unique_spec.rvfi_order.eq(cpu.rvfi.order)
+        m.d.comb += unique_spec.trig.eq(1)
+        m.d.comb += unique_spec.check.eq(1)
+
+        return m
+
+class UniqueTestCase(FHDLTestCase):
+    def verify(self):
+        self.assertFormal(UniqueSpec(), mode="bmc", depth=12, engine="smtbmc --nopresat")
+
 print('*' * 80)
 print('*' + ' ' * 78 + '*')
 print('*                        Verifying the Minerva core ...                        *')
@@ -265,6 +285,9 @@ CausalTestCase().verify()
 print("Verifying liveness checks ...")
 LivenessTestCase().verify()
 
+print("Verifying uniqueness checks ...")
+UniqueTestCase().verify()
+
 print('*' * 80)
 print('*' + ' ' * 78 + '*')
 print('*                      All verification tasks successful!                      *')