Why does Walmart sell the same jug holder for $29.00 with free delivery ?

I tried to order it from Walmart and it was a scam. I never got my water bottle holder. They ended up giving me my money back.

Can I stack up 5 tiers safely for 5 gallon jugs?

I buy the 3 and 4 tiers and had no problems at all . It’s very strong, so I imagined that the 5 tiers will be good too.

Can you make this a 5 tier tower?

It becomes more unstable the taller you go with out anything beside it - currently I only have a 4 tier - you could do a 3 tier with a 2 tier beside it but that takes more width space

Can i use this to stack two high?

Multiple 4 Tray Systems should not be stacked vertically. You can, however, connect multiple units horizontally using the Bottle Buddy Premium Connector Kit: https://www.amazon.com/Bottle-Buddy-TBB80008-Connector-Kit-Black/dp/B01LQ802DE. There are several other Bottle Buddy systems that allow you to store more than four bottles as well; such as the 3-3 Storage System or the 12 Tray System. To browse other Bottle Buddy Systems follow this link: https://www.amazon.com/stores/page/E8DD1742-8294-4354-B64A-483BF0D14126?ingress=3&visitId=090fa41b-ad9d-4ae7-b846-25f36ca5256f