Hi,
Two B1iSNs/Integration Frameworks can't be technically installed on the same server.
But it's possible to connect two separate B1iSNs/Integration Frameworks installations with one B1 server.
B1iSN9.0 and the Integration Framework are fully compatible: Only one B1 Event Sender must be installed, you need to handover B1 Events using the "B1 Event Subscriber" method.
Best regards
Bastian
P.S.: B1iSN8.8 is out-of-maintenance and not compatible with the Integration Framework.