Transaction fees are always included in a block. The entire block reward = subsidies + transaction fees are paid to the node who's block is ultimately accepted by the entire network.
When two nodes publish the same block it creates a split in the network. That split will be resolved by which block is solved next. The resolution is called a re-org. One block becomes part of the continually chain, the other is oprhaned to die a worthless death.
The network is actually more careful. Any revenue from a block is "locked" for 120 blocks not 6 blocks to avoid a situation where generation coins could be double spent due to a re-org.