Yes that's a typical reason for series. when you don't need head pressure. You would need a swing checks or spring checks to counter short circuiting. I prefer swing checks, less flow restriction. It would be nice to see some new options come up for the larger water cooling builds. It is possible to put a check on the pump itself.One side note the reason i chose series was for redundancy since check valves are not common place in computer liquid cooling. In parallel if 1 pump fails and there is no check valves the least restrictive path will be backwards through the other pump. I think your diagram actually covers that (that is a check valve after the pump isn't it?) just not everyone has played with dual pumps to even encounter that information.
In series if one pump dies it isn't much worse than having an extra 90' elbow in the loop depending on the pump model.
*I had the dual pumps when the mayhem pastel separated on me