Sorry, but this is not true.
The Hublot uses a modded 7750, just like the reps. How can you be sure? Apart from the photos of the movement showing the "7750" text clearly, the 7753 cannot change date with the crown. As there is no pusher at 10 o' clock, it's not a 7753. The last piece of proof it's a modded 7750 is that the date is recessed, just like on the reps. This is why the Big Bang is so accurate a replication.
If that's not enough proof, look to Hublot's documentation where they repeatedly say they're using the 7750. Why do they not use a 7753? Because they're cheapskates, just like the replica makers.
Can we please lay the false assumption it's a 7753 to rest now?