Numbers in iPad creates multiple copies of files

Recently I tried accessing a Numbers file from my iPad. The file is stored in a Dropbox folder. When I do so multiple copies of the file are created. Each copy has "(Eric Weir's conflicted copy)" added to the filename and each copy is consecutively numbered.

It seems that what's happening is that every time information is entered to a cell of the spreadsheet a new copy of the file with the updated information is created.

A perhaps related matter: I don't find a way to save Numbers files when using the app on an iPad.