MB102 BreadBoard Power Module Question
The MB-102 has a single 5 volt supply, with two output connections, and likewise a single 3.3 volt supply, with two output connections. The 5 volt and 3.3 volt supplies have a common ground connection.  This can be easily seen by looking at the schematic diagram.

You cannot treat the outputs of this board as separate supplies, nor connect them in series to create a +/- 5 volt supply.