Thats actually a board member here who posted that. Would be much cheaper to buy the corresponding Adventure or More Fun.
How would you know the difference?
Most Adventure and More Fun's were cut shorter than Actions and Detectives. Otherwise there is no way to tell. The asking price on ebay is downright silly. You can buy a complete More Fun 44 for $500 and take the back cover from that.
In most cases, corresponding month/year of Action, Detective, Adventure, and More Fun had the same back covers.