Our news media is so agenda driven, making stuff up or re-writing stuff to suit their own nefarious purposes, its hard to believe what's the real story anymore.
If the Saudis sold or leased the tanks to them, then of course it would be true that the tanks were Bahraini. THis way, the Saudis could avoid many complications. Particularly if the tank crews were awarded dual Saudi/Bahraini citizenship for the duration of the unrest. Much like the French commandos were converted to Islam before being let into Mecca to take down the rebels that held the Kaaba a few years ago.