We're going to install a Kirivans double seat swivel to allow the front passenger double seat to be swivelled around to face the back of the van, so I thought I'd see how much work it was to remove the seat. All the instructions and forums indicated there should be 8 bolts holding it down, but there are only 6!

Its possible someone replaced a single with this double and didnt put all the bolts in? The two holes are in the floor under the mat, but there are no captive nuts or anything in them. 

Is it safe with just 6 bolts?