All depends if you're talking about time [LDS say "no" here"], once upon a time [obviously yes, from the original leaders on down], or eternity [another "yes"--something LDS common folk don't want non-LDS common folk to understand].
In other words, LDS believe in past-tense polygamy, future-tense spiritual polygamy. They just frown on present-tense polygamy.
I used to live in Utah. I've had Mormon friends all my life.
Yes, I am aware of all this.