how many valve springs per Valve ? 273 hp

on a 65 oem 273 commando engine ... how many valve springs per valve ?

I thought the commando engine had two valves springs per valve and maybe a dampener too loke the 340 .

my 273 only has one valve spring per valve.

just wondering if it may have had a valve job over the years and not put back to stock .

Thanks for any infomation !
john