Given that you are referring to Tier Points, I assume that you are crediting to BA.

It would seem that your outbound journey was booked in either B,H or Y booking class and that the inbound journey was booked in a different booking class

Bookings in B,H or Y class will earn full miles and will earn Tier Points.
Bookings in any other economy class earn 25% miles and no Tier Points

Check your original booking and see what the booking classes were.

If they were in BHY out and something else back, then it is correct

If you were in BH or Y in both directtions, then contact BAEC and get the inbound points corrected

If you were in a discount booking class in both directions, then keep quiet and enjoy the points error in your favour

Dave