Fantasy Baseball Optimal Lineup - Problem With Multiple Player Positions

I am using Opensolver to create an optimal fantasy baseball lineup using projected points under the constraints of a salary cap. I have everything working, but the one problem that I am running into is when players have multiple position listings. For example, in the attached screenshot, you can see the player Todd Frazier is listed as both a 1B and 3B, and accordingly, the optimal lineup solution includes him being used in both positions. I need to figure out how to limit the use of Todd Frazier (or any player who has multiple positions) to be used for either one position or the other.

The attached screenshot shows the model and output.

Thanks in advance for your help.

Clint