A B737NG Captain took strong exception to Ground Control's preferential treatment for pilots of a competing Air Carrier at LAS.

Narrative

While taxiing to our gate; Ground Control instructed us to 'taxi south on taxiway 'G' and hold short of taxiway B for a west bound Air Carrier 'A' aircraft. After they pass you are cleared to taxi via taxiway B to C6'. After they passed I began spooling the engines up and began my left turn onto taxiway B when an Air Carrier 'B' aircraft began taxiing onto taxiway B from B6. We were already in front of them when Ground Control called us Air Carrier 'B' flight 123 (confusing our flight number with Air Carrier 'B') and told us to stop and let Air Carrier 'B' pass in front of us. It was way too late to give this instruction; because we were now in front of them on about a 45 degree angle. I would of hit him but saw him at the last second and unloaded out of my turn to avoid him. This aircraft didn't have authorization to taxi in front of us. Air Carrier 'B's' pilots; at that intersection; constantly try to force the Ground Controller to give them the priority by taxiing fast to that point and sometimes go beyond the hold line to get the preferential treatment. This incident was the second event for me taxiing in from that G taxiway towards the gate. We informed the Ground Controller that we were the ones who had been given the clearance to taxi and not Air Carrier B. This is the good part: the Ground Controller then apologized to the Air Carrier 'B' pilots for his error. Then instructed us to continue taxiing. Unbelievable!ZZZ Ground Controllers are creating dangerous situations by trying to squeeze Air Carrier 'B's' aircraft into places(ahead of other aircraft) because of their taxi speed on the ground; thus endangering other aircraft. The Ground Controllers need to focus on safety and not on Air Carrier 'B'.