I read up on the last time it happened just recently...
Jimmy Johnson in 1989 the last to do it with Boys, taking Troy Aikmen in the NFL Draft and Steve Walsh in the Supplemental.
All it did was create controversy and it wasn't until the Boys got rid of Walsh and put their faith in Aikmen that they came good. It could be argued that it was the right move because they did get their guy with one of the two picks but it has not been attempted since, at least that early on in the draft.
With still numerous holes to fill Dorsey would be a moron to even consider it.
49ers were going to do it in 2006 with Rodgers and Smith if Rodgers slipped another 8 places