Genesis Review Copy / Prototype ? help needed.

Hey All, I've been a long time reader and I'm starting to go through my video game collection I had stashed away for years and figured some of the lovely guys here would help me out... one of the things im not sure about are these two cartridges from my collection; any insight would be great

 

They look to be 1:1 review copies, i have a few sega and snes games that have labels just like that and there pretty much byte for byte the same as retail.

 

They may have EPROM chips open the cart up and have a look

 

Not the most exciting game, but pretty cool nonetheless.

 

how would I open one up?

 

Do they feel heavier than normal Genesis carts?

Only way to know for sure if they are the same as final build would be to dump them and compare.