"i am installing 2 100 amp breaker boxes for a duplex from a double meter the one wire has to go through the basement of one side do I need a disconnect and I keep hearing I need to run a 4 wire to what will be called the sub panel after I put in the 100 amp disconnect

Yes, the cable that leaves a meter cannot go much more than ten feet inside the building without short circuit protection, so a disconnect is needed at the meter and from that point on 4 wire cable is needed.

At this panel the neutral bar must be insulated and separate from the equipment grounds.

There is a bonding strip that came with the disconnect. I have wired houses before just never did a duplex.This whole 4 wire thing has got me just a little confused.Is there a diagram anywhere to see this

Are you an electrician?

The issue is not between a single family home and a duplex.

The issue is where the neutral gets bonded to the equipment ground.

Only at the Main Service Disconnecting Means, or before, but never after this disconnect.

After the MSDM, the neutral shall not be connected to any equipment ground.