Rules on multiple holdings?

Hey all,

I'm running two holdings in Quimby, separate enterprises, which are located very far from each other geographically so they wouldn't interact in any way. Today I noticed a player running two holdings in directly adjacent countries, and operating flights to some of the same cities. 

My question is, is this allowed? 


It is allowed as long as both holdings do not have any business relationship (interlining, lease of aircrafts, shares)

Clear enough! Thanks for the answer!