Answer:
No. Two placentas indicates dizygotic twins which always has 2 amnions and 2 chorions.
This is a common misconception. My own twins are identical, yet they had separate sacs and separate placentas that implanted on polar opposite sides of the uterus. DNA tested have proven their zygosity. Whether identical twins will have their own placentas is dependent upon when the egg split. In my case, the egg probably splip immediately after conception and conception likely took place in the fallopian tube.