POSSIBLE STUPID QUESTION ALERT 
I'm thinking about playing a keyboard as well as my P-Bass live, since many of our band's songs are modern dance covers; plus, I love playing keys and it'd be fun!
I'm trying to figure out the most efficient way to do it, without having to bring much more to gigs then I usually do.
Say my rig for a night consists of TWO Little Mark II heads (one for bass and one for synth) and ONE 2x10 cabinet. Could I send the speaker out of both heads into ONE cabinet, without doing any harm?

I'm thinking about playing a keyboard as well as my P-Bass live, since many of our band's songs are modern dance covers; plus, I love playing keys and it'd be fun!
I'm trying to figure out the most efficient way to do it, without having to bring much more to gigs then I usually do.
Say my rig for a night consists of TWO Little Mark II heads (one for bass and one for synth) and ONE 2x10 cabinet. Could I send the speaker out of both heads into ONE cabinet, without doing any harm?