There's at least one internet creation in there, possibly several more (no, not the Tsar tank or the Kugelpanzer, they're both real). The M15A GMC is clearly based on a picture of a photoshopped M3 that's on the web. I'm not certain there's even physically room for the gun breeches, there's certainly no room for the crew. The actual M15 in the GMC numbering series is the M15 CGMC AA halftrack.
It's also fairly unlikely a US tank created during WWI (CLB 75) used 6 Brens as armament!
So treat with caution.
Most of them only look weird if you're solely used to contemporary tanks, things like the tankettes and the multi-turret designs were absolutely standard in the interwar period.