Hi
do you really need to create different tabs for each month to enter your data?
It would be much simpler to enter your data in one sheet ( with a column for dates) for analysis or detecting duplicate entries.
Pivot Tables with slicers would allow extracting monthly data or whatever needed.
If you wish to keep you actuallayout,to help us help you it would be advisable to post a sample sheet with some data ( mocked up if needed) so we can see your data layout