When Lance Bouma was with the Vancouver Giants and Abbotsford Heat, he wore the number 10. When he joined the Flames, it was under his training camp number of 57. When he made the team full time, he ended up with #17 - as Corban Knight, freshly traded for, was immediately granted #10.
Bouma played more NHL games than Knight that season. (Bouma played more NHL games that season than Knight has in his entire career.) One of these players is still with the Flames - and he ended up with a slightly higher number than may have been originally anticipated.