Crop Circles expansion - Do players HAVE to place a meeple?
The crop circle rules are slightly ambiguous but my reading of option A is that all players MAY place an extra follower on a tile they have a follower, but if they do it MUST be with a follower of the same type.

I think it reads better if you put the rules together rather than separating them.

He then decides for every player, starting with the player to his left, if:
A) they can place another follower on a tile where they already have a follower
of the type designated by the crop circle.... the player must place the new follower with another one of his followers of the same type (a farmer with a farmer, a thief with a thief, a knight with a knight).