Peter:

They do make Unistrut Couplings (joiners) which would serve the same purpose.

You can see some here:
http://www.unistrut.com/Browse/cat_detail.php?S=S07&P=P2900

and see all of them here: http://www.unistrut.com/Browse/cat_pg.php?P=S07_Elect

"If common sense was common, everyone would have it"-not sure, someone here