That is absolutely correct – the strings are tuned differently.  I use a 12 string for recording – BUT – I dial up the stock 12 string patch live, and with the interplay of all that goes on with sound in a live environment, it does the trick in many cases.   

That said,  I am not plugged into million dollar live sound rigs that can really distribute the signal effectively.  I get whatever has been subcontracted and thats good for me.

Best regareds

L