No one is forced, everyone has the choice to accept or reject. Free will operates in the spirit world just as it does in this one. Some people have had work done multiple times, usually because they have many descendants who are Mormons, and because, until very recently, it was difficult to find out if the work had already been done. My 8th great-grandfather was Miles Standish, of Mayflower fame, and I have found over 200 instances of baptisms being performed for him, from the mid-1800s until 2008 (the last year I checked). He literally has millions of descendants in the US. All this duplication is unfortunate, as it wastes time and resources that could have been used to do others' work, but has no eternal consequences for Capt Standish.