I never knew either man so I don't know if that ever happened. Mohammed claimed to have seen God/Allah but it is difficult to believe the Qu'ran has anything at all in common with the God revealed in the Biblical scriptures and known to billions of Christians. Joseph Smith claimed to have seen God as a youth, and to have received the golden plates, basis for the Book of Mormon, from the Angel Moroni. The plates were returned to Moroni after Smith translated them. I don't see much of the God of the Bible in the Book of Mormon either.
It is not given to me to judge the faith of anyone but only their actions. Islam has contributed quite a bit to the world, especially long ago, but its extremists are not only not Christian but are clear in their intent to stamp out JudeoChristianity entirely. That cannot come from the God of the Bible. The Church of Latter Day Saints has also been beneficial to many of its people, but also has its dark side that merits caution.