The 'first issue' of the newly named Sports Illustrated was published a few months after this 'dummy' in August, 1954. (I have 2 'first issue' of SI available on eBay)
My dad was in the sports and advertising business and has access and cared about first editions, etc. of all things sports.
Initially, I thought 'who in their right mind would call a magazine Dummy!?' I have posted a video, but eBay sometimes takes a long time to approve video. Please view all photos carefully.
I'm glad I looked a bit further into this and am quite smitten with the history, rarity of this prototype magazine! A wide range of sports topics from horse racing, boxing, golf, leisure, fishing, etc. Editor's notes are inside, crossword puzzle (one is printed upside down?) and just overall a great collectible item!! If you are a collector of sports memorabilia, this is without doubt something you want!