You can definitely do this as previously mentioned. You can rig the unit on a swivel so it can be turned, and run two transducers. You can also get an extra mount, power cable, and transducer and move it back and forth.

If you're looking at the lower priced units, Helix and lower, I recommend just getting two fish finders. The cost of an extra transducer, power cable, and mount usually are 60% of the cost of those units. For example, if you run a Helix SI at the console (stick), and want to buy an extra transducer for up front, it's a $200 part. The Helix DI and Helix DI GPS are $250 and $350, respectively- in this scenario, just rig a second unit.

If you're into the higher priced units, maybe go ahead and rig an extra transducer.