If it's just two players, it usually isn't a huge deal. Generally the big issue is bye weeks, but that's gone now. Starting two from the same team usually will guarantee a small level of safety. Its less risky, but potentially less rewarding.
Spot on assessment by Ryan. Typically if you start 2 players from the same team, especially 2 receivers, you want them to be the first and second options on their respective team. A great example would be Tomas/Decker or Colston/Graham. QB/WR is too boom or bust in my opinion unless it's an elite QB. Last year Smith/Cam was money in the bank but usually it doesn't work out like that. In your case if those are the best options you have I would go with them. Don't worry about the team situation, play your best players from here on out.