| I see what you mean
and they do look like standard 45mm pipes. It's possible that the mono 748 had an exhaust shield with those mounting brackets in your first pic. The second pic shows the mixer with the standard Bip exhaust shield mounting.
Has the chip been changed? Can you see if the sticker has been removed on the computer under your seat?
Could it be early 748SPS pipework? Look on the cans. The DUCATI logo should be stamped on them and if they are Termi standards they will also have Termignoni stamped on their somewhere. (Termi did some standard cans on some models) | 
Threaded Mode