Hi G'
"Now I have no reference to my original file that was created under another name, only the new one. "
Actually, what you have now is the same file with the original name replaced by the new name.
If you wanted two copies of the file, one with each name, you should have used option-File > Save as…
- (Press and hold option key, click File, choose Save as…, release option key)
- Then give the file a new name (and, if desired, a new location) and click Save.
That two step process keeps the old version of the file (and its history) under the old name, and saves the current version of the file as a NEW file with the name assigned during Save as….
The NEW file becomes the active file open in Numbers.
Regards,
Barry