The absolute definitive answer is: MAYBE.
WikiTree does not provide capability to overwrite a file by upload and does not permit you to choose the name a file will be stored on the server. For these reasons, you have no control of the name that will be assigned to the file when you upload it.
Where the "maybe" comes in is that if you delete a file ... oops, this is another capability you don't have! The only way a file gets deleted is to remove all page attachments to it and wait a day or two ... or maybe more ... until the system detects that the file is not attached to any pages and then the system deletes the file.
When a name is assigned to an uploaded file, it will be the first available name using the convention of pagename-#.jpg, pagename-#.gif, or pagename-#.png, or pagename-#.pdf where pagename is the WikiTree ID or name of a freespace page and the extension indicates the file type. The first file you upload of any file type does not have the "-#" in its name. After that, the # starts with 1 (for the second file of that type) and the numbers increase with each additional file.
Here's where the "maybe" comes in -
- Remove all the page connections for an image
- Do not upload anything else to that page for a few days
- Upload the replacement file
- You have a good chance that the replacement file will have the same name as the one that was deleted.
Please do not ask my opinion of how the system works.