Amount of allowed tickets

Hello Daniel-san.
Currently, I am planning a travel route for my holiday in Japan (October-early December) and I plan to visit some cities/regions that are covered by some regional passes.

I might want to stay longer than the predefined range from a regional pass.
Is it therefore possible to buy a second regional pass from the same region or is it limited to one ticket per person for the entire holiday?

My second question is about when I should order the passes. Is early-mid September early enough? ( I heard the voucher is valid for three months)

Kind regards,
Domenic