Ready for that tinfoil hat?! Take a look at the language used to describe the covers:
Venom #1:
Color
B&W
Secret
Venom #2
Color
B&W
Symbiote
It'd be really cool if the color and B&W covers were of the host, and the third cover a separate image of the symbiote of Venom.
Might be a stretch. One of the owners involved with these said on a podcast that they named it "secret" because they had no clue what type of cover the limited run would be at the time they commissioned it. Also if you look at some of the other names for other limited run books on the sales page they are theme names as well.
Let's call it wishful thinking but realistically I assume it will be one image with three different versions, i.e. color, b&w, then one virgin/pink/rainbow etc.