Multiple m1 stores into single m2 store?

Hi Zeno,
Our UB Data Migration Pro allows you to migrate both Magento 1.9 into the same Magento 2 instance, however there’re a few things you should note: 

• After migrating data from the first Magento 1.9 db, there’re a few extra manual configuration steps before you can continue migrating from the 2nd Magento 1.9 db (We will provide you detailed instruction, if you purchase our Pro version).
• If you plan to run delta migration at a later phase, then you can only proceed delta migration for the 2nd Magento 1.9 database only.

And with our current subscription, you can install on multiple Magento 2 instances, however you’re allowed to migrate from one single Magento 1 database only. So, you will need two licenses under this circumstance.
PS. Please note our Pro version supports Magento CE to CE migration only.
Regards,
Ubertheme team