From the menu File - Options - Misc there is the function “Merge transpositions”.

 

 

This function has to do with the merging of games. In ChessBase the user can highlight several games in a games list and bring them together in a variation tree.

 

E.g.

 

1.e4 d6 2.d4 d5

1.d4 d6 2.e4 d5

 

You can choose to merge these games with the function, or not; we are dealing with frequently occurring transpositions of moves.