Aloha Steve,
Just to be sure. Last night I did this 4x:
Repro:
Open a track in Score Edit
Switch to page view mode
Print the score to pdf.
No probs.
Then I did this 4x:
Repro:
Open a track in Score Edit
Switch to page view mode
Print the score to pdf. Use a file name that already exists when the save dialog comes up
Hit Save
No probs
But this was after a gig so it may well have have been pilot error.
So today after coffee I tried both again 1x (right now).
1st example: Still no probs.
2nd example PROBS! as described.
—go figure this one. I’m sad. 
{‘-’}