If a football player A fouls player B in a manner such that they will receive a yellow card, but the referee plays the advantage rule, and subsequently player A fouls another player, can the referee give him two yellow cards, and hence a red card, one for each foul, or does player A get only the one yellow?
Yes. If both the offences deserve a yellow card each, the referee is obligated to show the player two yellows (and hence a red card). The referee must indicate that the first yellow is for the first offence and the subsequent yellow for the second offence.
After the second offence, the referee must stop play immediately unless there is a clear goal scoring opportunity. Advantage may not be played on sending-off offences unless a clear goal scoring opportunity is present.
See FIFA Laws of the Game 2015/16 page 73