Boko Haram Islamist militants have not claimed the blasts, but the group has repeatedly targeted Kano, including bus stations, throughout its six-year uprising.
"The victims included 21 passengers in a bus that was about to leave for its destination, three of our members and 10 petty traders," said Ahmed Saleh, of the National Union of Road Transport Workers (NURTW), who is based at the targeted Kano Line station.
Kano police spokesman Musa Magaji Majia told AFP that the force's official toll remained at 10 dead.
Two men blew themselves up shortly after getting off a bus at the station, causing chaos at the station and scattering blood and human flesh around the site.
Nigeria's is struggling to control Islamist violence ahead of March 28 general elections.
The vote had been scheduled for February 14, but security chiefs pushed for a six-week delay, saying the postponement would provide extra time to weaken Boko Haram before polling day.