Hi Rouven,
Bridges create a simple L2 link, so think of these two links as being nothing more than long Ethernet cables. When you plug the two "cables" into their switches, you'll create a network loop. So you have two options:
1. Allow Spanning-Tree to block the loop
2. Configure Etherchannel on the switches to bond the two links
Take a look here for some good Etherchannel documentation: https://www.cisco.com/en/US/tech/tk389/tk213/tsd_technology_support_protocol_home.html
I hope this helps.
Jeff