Reporting with the BEX Browser on two systems

Within the next weeks, we will migrate a number of data models from our BW (BW1) to another BW system (BW2). Some users will have acces to both BW1 and BW2. We are working with the BEX Browser and we want our users to be able to report on both BW's by opening the BEX Browser for BW1 and opening the BEX Browser in a new session for BW2.

Until here everything works fine. If we execute a BEX Analyzer report on the browser for BW1, the BW1 report is opened. However, if we execute a BEX Analyzer report in the browser for BW2, BEX analyzer is opened but the report itself is NOT.

Can you advise us how we can correct this issue?