diff --git a/include/cantera/kinetics/StoichManager.h b/include/cantera/kinetics/StoichManager.h
index bd9cb0850..34f20afd7 100644
--- a/include/cantera/kinetics/StoichManager.h
+++ b/include/cantera/kinetics/StoichManager.h
@@ -771,7 +771,7 @@ public:
         }
         bool frac = false;
         for (size_t n = 0; n < stoich.size(); n++) {
-            if (fmod(stoich[n], 1.0) || fmod(order[n], 1.0)) {
+            if (fmod(stoich[n], 1.0) || stoich[n] != order[n]) {
                 frac = true;
                 break;
             }
diff --git a/interfaces/cython/cantera/test/test_kinetics.py b/interfaces/cython/cantera/test/test_kinetics.py
index 978f31bbb..75944337b 100644
--- a/interfaces/cython/cantera/test/test_kinetics.py
+++ b/interfaces/cython/cantera/test/test_kinetics.py
@@ -426,8 +426,8 @@ class ExplicitForwardOrderTest(utilities.CanteraTest):
     def test_irreversibility(self):
         # Reactions are irreversible
         Rr = self.gas.reverse_rate_constants
-        self.assertEqual(Rr[0], 0.0)
-        self.assertEqual(Rr[1], 0.0)
+        for i in range(3):
+            self.assertEqual(Rr[i], 0.0)
 
     def test_rateConstants(self):
         # species order: [H, AR, R1A, R1B, P1]
@@ -436,6 +436,7 @@ class ExplicitForwardOrderTest(utilities.CanteraTest):
         kf = self.gas.forward_rate_constants
         self.assertNear(Rf[0], kf[0] * C[2]**1.5 * C[3]**0.5)
         self.assertNear(Rf[1], kf[1] * C[0]**1.0 * C[4]**0.2)
+        self.assertNear(Rf[2], kf[2] * C[2]**3.0)
 
     def test_ratio1(self):
         rop1 = self.gas.forward_rates_of_progress
@@ -445,6 +446,7 @@ class ExplicitForwardOrderTest(utilities.CanteraTest):
         ratio = rop2/rop1
         self.assertNear(ratio[0], 2**1.5) # order of R1A is 1.5
         self.assertNear(ratio[1], 2**1.0) # order of H is 1.0
+        self.assertNear(ratio[2], 2**3) # order of R1A is 3
 
     def test_ratio2(self):
         rop1 = self.gas.forward_rates_of_progress
@@ -454,6 +456,7 @@ class ExplicitForwardOrderTest(utilities.CanteraTest):
         ratio = rop2/rop1
         self.assertNear(ratio[0], 2**0.5) # order of R1B is 0.5
         self.assertNear(ratio[1], 2**0.2) # order of P1 is 1.0
+        self.assertNear(ratio[2], 2**0.0) # order of R1B is 0
 
 
 class TestSofcKinetics(utilities.CanteraTest):
diff --git a/test/data/explicit-forward-order.inp b/test/data/explicit-forward-order.inp
index 0c0915fb1..345af1d9e 100644
--- a/test/data/explicit-forward-order.inp
+++ b/test/data/explicit-forward-order.inp
@@ -13,8 +13,14 @@ REACTIONS
 R1A+R1B=>H+P1              1e12  0.0   20000.0
   FORD / R1A 1.5 /
   FORD / R1B 0.5 /
+  DUPLICATE
 
 H+P1=>R1A+R1B             5e13 -2.0 5000.0
   FORD / P1 0.2 /
 
+R1A+R1B=>H+P1              1e12  0.0   20000.0
+  FORD / R1A 3.0 /
+  FORD / R1B 0.0 /
+  DUPLICATE
+
 END
diff --git a/test/data/explicit-forward-order.xml b/test/data/explicit-forward-order.xml
index 549a43706..7632526a1 100644
--- a/test/data/explicit-forward-order.xml
+++ b/test/data/explicit-forward-order.xml
@@ -108,7 +108,7 @@
   <reactionData id="reaction_data">
 
     <!-- reaction 0001    -->
-    <reaction reversible="no" id="0001">
+    <reaction duplicate="yes" reversible="no" id="0001">
       <equation>R1A + R1B =] H + P1</equation>
       <order species="R1B">0.5</order>
       <order species="R1A">1.5</order>
@@ -138,5 +138,21 @@
       <reactants>H:1.0 P1:1</reactants>
       <products>R1B:1 R1A:1.0</products>
     </reaction>
+
+    <!-- reaction 0003    -->
+    <reaction duplicate="yes" reversible="no" id="0003">
+      <equation>R1A + R1B =] H + P1</equation>
+      <order species="R1B">0.0</order>
+      <order species="R1A">3.0</order>
+      <rateCoeff>
+        <Arrhenius>
+           <A>1.000000E+06</A>
+           <b>0.0</b>
+           <E units="cal/mol">20000.000000</E>
+        </Arrhenius>
+      </rateCoeff>
+      <reactants>R1B:1 R1A:1.0</reactants>
+      <products>H:1.0 P1:1</products>
+    </reaction>
   </reactionData>
 </ctml>