factual error?

"During Falco's first play in the Dallas game (kick ass on one), the ref calls multiple unnecessary roughness calls and then wonders how many penalty yards to give. In Pro football, only one penalty may be called per team per play, so it wouldn't matter how many people got caught, only one unnecessary roughness penalty would be called, for 15 yards."

Is this right? I know for in play fouls and 5 yard penalties, such is usually the case but i thought personal fouls such as unnecessary roughness and unsportsmanlike can be cumulative and thus teams can get penalized multiple times per play.

I know this is the case for unsportsmanlike penalties. If you recall the year the patriots went 18*-1, they won a regular season game against baltimore mainly due to favourable officiating late in the game (it was even confirmed the officials were taunting the ravens). Bart Scott of the ravens was assessed two 15 yard unsportsmanlike penalties on the same play resulting in 30 yards; he said something to the official to get one and then when the official threw the flag, he picked it up and tossed it into the crowd.