I have never seen such behaviour (in all my days). And now I tried to provoke it and still I failed. (As simultaneously as possible, or first use and then map, or first map and then use).
Then I tried the following console tricks (roughly from memory):
.. and some more. Didn't get that. I do wonder how you managed.
.... No, actually... Now I did it. Manually. Trying to hold one or the other while pressing the other while chargin at the switch. Hm. Bug report? Seems buggy.
And I have managed a couple of times by toggling the automap rapidly and pressing +use.
Effective provocation:
Console: alias freakmap "togglemap; wait 1; freakmap"
Console: freakmap
Now you're pressing that button on and off all the time. Now you can't end the level.
EDIT: Actually, you can. It probably happens only when turning automap on (or off), not both ways.
I posted a bug report on it a long time ago when it first happened to me. It was deemed unreproducible and dropped. For the slim chance of encountering the bug, it's not really a big deal to be fixed.
For a moment there I thought you called out the original artwork as a fake... Well; the bug report is submitted, and a feasible means of reproduction (asexual) has been suggested.