Stitching

If MichelBParis's suggestion does not work for you, create a canvas of sufficient size to accommodate music pages A & B.

1. Go to File>New>Blank file, enter H&W of the paper stock
2. Then, for A go to Select>all, then Edit>copy
3. Go back to the canvas, then Edit>paste. A will come in on a separate layer
4. Repeat for B
5. Use the move tool to align/position A&B

wrote Elements 2018 I have scanned a page of music in two sections because the format is bigger than my A4 scanner. The scans are .psd format and gray scale. I then tried to stitch the two using photomerge under the guided tab and get the following error.  "The command duplicate is not currently available" Any suggestions? Can I attach the files to my discussion? John McWilliam

My guess is that you have to convert those files from grayscale to RGB first.

Menu Image >> mode >> RGB Color