I'm aware of two ROM variants for Super Pro Football but only one of these two is from an actual cartridge.
checksum crc32: 83141d85
The cartridge version has a minor glitch on Intellivision II. According to intellivisionlives.com the quarterback does not appear until the ball is hiked but otherwise plays normally. An errata slip was included in some boxes (see intvfunhouse.com). I'm assuming this version has this behavior as it hasn't been tested on a real Intellivision II. If someone can confirm this on a real Intellivision II please post.
Intellivision Lives! PC/Mac
checksum crc32: 32076e9d
This is the version that is commonly found on the ROM sharing sites. This version should crash an Intellivision II but plays correctly on the original. In emulation it crashes immediately after finishing with the setup screens using Intellivision II exec. Intvnut wrote-up an explanation here: http://atariage.com/...tion/?p=3596200. If anyone has an Intellivision II and flash cartridge maybe they can confirm this behaviour on real hardware. I'm thinking that after the disappearing quarterback glitch on the cartridge release, they tried to fix the problem. This version has code that specifically checks for different Execs and only runs specific code that crashes the game on an Intellivision II. Maybe they started to fix the problem and either didn't finish or this is a preliminary version that ended up on Intellivision Lives! CDs.
There could be a third ROM variant that perhaps runs correctly on an Intellivision II. Again if anyone has a version on cartridge or file that behaves differently please post.