Hi!
Sorry for the late reply on this. I usually try to do at least a weekly pass on the forums but it's been a particularly busy week.
Glad to see you've resolved your problem though. Just to ensure that things are behaving correctly, when you try to assign the same key to two actions at the same time, SOMA does allow this, but it pops up a warning letting you know what you've done.
In your example, interact and cancel interact would end up cancelling each other out.
These are highlighted in Red when you do this. By default, we have Cancel and Throw on the same button (RMB) and since these two actions never occur at the same time, they never conflict.
A popup warning is given when you try to set up a custom config like this, just to advise you as to what you are doing.
Sorry to hear you had some difficulty with this, but glad you got it all resolved!
- Steve