Strange buying of tickets R2

It is probably not waht you would actually call a bug, but I did not no where else to put it:

It happened that I started flights on a route with strong competition in C and Y seats (TXL-CPH, more than 3 times as many seats than demand). Eventually it turned out for me that I made most profit when setting the C price to $99 and the Y price to $129, getting 73% loadfactor in C and 48% loadfactor in Y. Although I guess that this arises from the fact that Y and C seats are calculated separately and therefore there is no actual bug, it is a rather strange behaviour of the passengers going for the more expensive Y seats when there are cheaper C tickets available, isn't it?

In case you want to reproduce, here the seats (daily) and ticket prices :

Airline A: 66 C ($99), 621 Y ($50)
Airline B: 1 C ($164), 21 Y ($75)
Airline C: 51 C ($99), 480 Y ($129)
Airline D: 64 C ($99), 592 Y ($56)