My ISL has the same two fuel filters, in the same location, AND the one on the left (in your pic) side of the engine near the oil filter. I had no idea it was there for many years, and just replaced the two filters in your pic. I have not replaced the fuel filter on the left side of the Engine yet, but know it is just a matter of time and I'll have to do it. Not looking forward to it, especially after reading this post.
Bill