devtrackers.gg
Just FYI if you accidentally ctrl-click a map into your Map Stash and lose track of it, you can switch to the map tab and it will show you the correct subtab for that map (the most recently deposited map).
Otherwise (e.g. if you accidentally ctrl-click two maps) you can simply search for it with the in-game search box, e.g. "Elder" or "Occupied". As long as you don't leave the area, the game knows about all maps you have placed while in the area and can find it.
If you leave the area then all stashes are unloaded for performance reasons, so it's more difficult.
Unfortunately this isn't always the case (even when the current tab is the map tab). There's a bug that occasionally causes a control + clicked map to be added to the map tab without loading the correct sub-tab (the sub-tab will show an incorrect number of maps and searching for the added map doesn't always work--or doesn't work at all if searching for some unique string on the map; ie: in the vid if I didn't have another Palace my search wouldn't have shown any results).
This appears to happen rarely when quickly manipulating multiple map items across multiple subtabs, but is more common with high server latency and/or packet loss. I'll see if I can fix it.
[EDIT]: You can fix it by closing the stash and reopening it. This will cause all "lost" maps to reappear, and be searchable with the search bar.