OK for same employer to have 2 different 401(k) plans? One will be safe harbor, other will be subject to ADP testing

[Guest RSNOW]

Does anyone see any problem with an employer who wants to start up 2 separate 401(k) plans where one would be safe-harbor and one would be subject to ADP testing. They have 4 HCEs and would basically be splitting them up (2 and 2) in each plan to pass 401(b). Is there anything in the safe-harbor regs that would require ALL employees under both plans to get safe-harbor match/contributions, or can we just provide safe-harbor benefits to those NHCEs under safe-harbor plan only ? Thanks in advance.