Hi Robin! Try using the shift button to collect both, OR come in from the top view and then select the 2 faces, OR
2)with the faces tool, you can 1> match 2>move etc. the faces. there are times when the sequencing does matter what you do when, and it seems this is one of those moments, hopefully, you have had the file open a few days now, so by going through the edit> undo, then do a file/save as, you will have a "pickup point" without losing more substantial time.