On project load, ensure reverse mixes are correctly detected

src/timeline2/model/builders/meltBuilder.cpp

@@ -282,6 +282,7 @@ bool constructTrackFromMelt(const std::shared_ptr<TimelineItemModel> &timeline,
             }
         }
     }
+    // Load same track mixes
     for (auto compo : qAsConst(compositions)) {
         timeline->plantMix(tid, compo);
     }

src/timeline2/model/trackmodel.cpp

@@ -2469,6 +2469,12 @@ bool TrackModel::loadMix(Mlt::Transition *t)
             field->unlock();
             return false;
         }
+    } else {
+        int firstClipIn = m_allClips[cid1]->getPosition();
+        if (in == firstClipIn) {
+            // Incorrecty detected revert mix
+            std::swap(cid1, cid2);
+        }
     }
     // Ensure in/out points are in sync with the clips
     int clipIn = m_allClips[cid2]->getPosition();