I am pricing a R/T MGA YYZ via MIA, in J, CDN$

One R/T MGA-YYZ-MGA 5/16 6/27 in D, with fare basis JCC (fully refundable) is CDN$2683.

One way MGA YYZ on 5/16 is $1,348
One way YYZ MGA on 6/27 is $1,090 for total of $2,438, so it's an easy save of about $250.

Both OW are in D, JCC fully refundable fare basis. In the case of the $1,090 fare the base fare is lower than the base fares for the same leg R/T and the taxes are much lower.

I cannot figure out why they are showing up D for that matter, other than D is plenty available but in all 3 cases the choice under select pricing option is Business Flexible. (For one-way there is no choice but).