This has come up a few times...
Currently there can only be one binding active per trigger. The UI won't prevent you from making several, but it will pick one of those at random when it builds out the binding table.
Mobius 2 allowed this, though the important thing to understand is that order that those bindings happened was random. People often misused this as an alternative to scripting, getting two things to happen one after the other, but the problem is that it was unreliable because you could not control the order. Sometimes it would work and sometimes it wouldn't. For Mobius 3, I decided to avoid the issue of binding order control and just not allow it.
For simple things like instant Mute of a few tracks order doesn't really matter but I was trying to keep people from getting into trouble. This has been requested several times from old Mobius 2 users so I need to revisit this and decide what we're going to do once and for all.