What is the ruling of signing a marriage contract with two wives in one day, or marrying four women in one day?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

It is permissible for a man to marry two wives in one day provided the conditions of a correct marriage are met and provided there are no marriage impediments. The evidence is the Saying of Allaah (which means): {…then marry those that please you of [other] women, two or three or four.}[Quran 4:3].

Since Allaah permitted a man to marry up to four wives, then there is no difference if he marries them all at once, or one after the other [at different times and intervals]. 

Allaah Knows best.