One service will be used for region A because it offers paypal, the second one will be used for region B (it does not have paypal option) but offers automatical generation and sending invoice for customers who will be paying by bank transfer as to bank details indicated in the invoice.
It's not just okay, it's a welcome addition to your website. This will allow you to sell your services to users who do not have paypal.
I personally use 2checkout for my clients' websites, which allows you to accept paypal payments, as well as Credit Card payments from almost all countries where Paypal is not supported.
It's always good to offer your consumers to choose from multiple payment accepting service, so they can all find what they’re looking for no mater were their located.
For example most consumers in Russia use Qiwi and in Sweden consumers like to use Klarna.
I can offer you to use ZooZ (I work there) that will give you multiple payment accepting service all in one box.
We offer: PayPal,Credit/Debit cards, Dwolla, ELV, Klarna, Qiwi and other e-wallets.