diff --git a/lib/Paneset/Paneset.js b/lib/Paneset/Paneset.js
index c6c96e2cb..838dbbd75 100644
--- a/lib/Paneset/Paneset.js
+++ b/lib/Paneset/Paneset.js
@@ -442,10 +442,15 @@ class Paneset extends React.Component {
           this.interval = null;
         });
       } else {
-        // insert sorted by left coordinate of clientrect...
-        const newPanes = insertByClientRect(newState.panes, paneObject);
-        newState = Object.assign(newState, { panes: newPanes, changeType: 'added' });
-        // newState = this.insertPaneObject(newState, paneObject);
+        // check for duplicate id's before registering. Registration happens on mount.
+        // This will help with mount-twice strict mode strangeness
+        const paneExists = newState.panes.findIndex((p) => p.id === paneObject.id)
+        if (paneExists === -1) {
+          // insert sorted by left coordinate of clientrect...
+          const newPanes = insertByClientRect(newState.panes, paneObject);
+          newState = Object.assign(newState, { panes: newPanes, changeType: 'added' });
+          // newState = this.insertPaneObject(newState, paneObject);
+        }
       }
       return newState;
     }, () => {