Pay for an issue I already purchased?!?

Im updating and changing my rating from one to three stars. I enjoy the content, but The process for retrieving my previously purchased June 2015 issue was very confusing. Read below:

I purchased the June 2015 issue on my iPhone with no problems. When I try to download it on my iPad it ask "Do I want to purchase one August 2015 for $4.99?" So my options are to BUY the August 2015 or cancel. What happened to the June 2015 issue that I purchased?!?

I finally went ahead and clicked buy and the app informed me that I already bought the issue and can download it for free. So now I have the issue on my iPad, but still found the whole process confusing.

Shark Marius about Mac|Life Magazine