User Somehow Able to Enter Duplicate MIGX_id's
One of our users was somehow able to start the MIGX_id counting again on a large grid, this caused the duplicates to take the place of the originals in getImageList even though they were still present. I had to go into the database, download the JSON and re-increment the MIGX_id values to get it working correctly again. I don't know if this is reproducible, I have never seen it happen before.
I had seen this once a long time ago with an older version of MIGX. I found a bug this time and fixed that. Never had seen this happen again, then.
For what it's worth, they are running MIGX 2.9.6-pl on MODX 2.5.4. I do not know what browser they were using. Their network connection is around 9Mbps. I thought maybe they did not for the grid to load.