You asked about the LDS faith (and it would be irresponsible to lump LDS in with Catholics) and what I have heard from RCIA is that most parishes will decide to rebaptize those who were baptized Mormon.
Yes, they baptize in the name of the the Father, Son, and Holy Spirit; but according to them who is the Father? He is a created being that started out quasipotent and ascended to the divine position he (lower case used intentionally) now occupies. Joseph Smith expressed a hope that he will one day occupy the place god now occupies as god moves on to yet a more exalted position. Sound familiar? <img src="/forum/images/graemlins/threaddevil.gif" alt="" />
And who, according to them, is the Son? He is also a concieved and created being raised by the father and his heavenly wife. (who knows who that could be) He, and his sibling, Lucifer, both presented plans for salvation; the father accepted Jesus's and rejected Lucifer's casting him down to earth.
And who then is the Holy Spirit, according to them? Not much emphasis is made of their holy spirit. In fact Joseph Smith at one time referred to him as the "mind" of the other two. (Lectures on Faith 48-49)
These beliefs contradict even the Book of Mormon, and are derived from the ever deviating sermons that Smith gave as his church developed.
Can you see why most RCIA directors hesitate to give validity to Mormon baptisms? But there is no reason, other than pure animosity toward the RCC, to reject a Catholic baptism as our accurate doctrine of the Trinity has remained constant these 2000 years. There is only one Father, Son, and Holy Spirit, and in the name of this most blessed and holy Trinity, we baptize.
In the Sacred Heart of Christ and the Immaculate Heart of Mary