They are both copies. They explain that the guy operating the transporter was losing him, so he used a second beam to try to compensate. On beam made it through, the other bounced off the st uff in the atmosphere that was causing the problem and rematerialized him on the planet. I'm pretty sure this explanation was in the episode in order to establish that both Rikers are equally real.
Except that that explanation means Tom was made with the original Riker materials and Will was made from matter reserves on the ship using the original Riker as a template.
Both beams were pulling in genuine Will Riker. Presumably they are both a mix of the original material and additional material formed by the transporter. That or the transporter is violating the law of conservation of energy.
This is a semantics argument. The way the person you're talking to means it, two things being equally fake also means that they're equally real, because they are both just as real as the other (that is, not).
i always felt that it was wrong that they gave the riker that got out a promotion; but wouldn't do the same thing for the riker that didn't get out even though he was the one who paid the price for his heroism while the other riker simply got lucky and both did the same thing that earned that promotion.