Thank you for your answer
Yes, and exactly I have
- in my booking on site i have
1 underseat bag (40x30x15 cm)
+ 1 carry-on bag (55x40x23 cm)

- in the ticket on email I have
Baggage
Allowance
0PC

- when I have do the reservation on the site, the site write
1 carry on during Bologna-Toronto
0 carry on during Toronto-Bologna. (During the reservation I was closer to buy an extra baggage only for the return flight!! Probably, I was closer to spend a lot for nothing)


Seem that SAS doesn't know how many baggage I can keep with me.