iPad synths in Logic, with midi keyboard, Hearing extra sounds

I'm using my iPad in logic through IDAM, and can hear my favorite synths. I also have an old midi keyboard (Yamaha P80) running into the computer through an M-Audio midi uno. When I play the keyboard, I hear the synth, but there is a distinct bell-like sound mixed in. when I take my finger off the key, it makes a dull-metallic sound on top of the bell sound. If the iPad is off, it just makes the dull sound.

If I play the synth on the iPad, that sound doesn't come through. It's only when I play the note on the physical keyboard.

If I hook the keyboard directly into the iPad with a camera kit, the keyboard works just fine.

Obviously something is routed incorrectly. Any thoughts?

thank you!