In September 2012, iPoker split their small stake cash and SNG NLHE traffic into two pools while still sharing traffic in promo SNGs, satellites, MTTs and other, less populated, games like PLO, HSNL or Stud.
First, the biggest skins with strong recreational player bases formed a ringfenced pool aka iPoker2 for small stake cash and SNGs, hiding them from the rest of the network. Harsh requirements were imposed on skins to enter and/or remain on iPoker2 - they've had to care a lot about acquiring recreational players ever since.
The other skins also suddenly stopped allowing the big ones into their games affected by the split, forming so-called iPoker1, which now has way smaller traffic because many players have switched to iPoker2 skins, and also because many extra skins have fulfilled the requirements.
It's impossible to be logged into both pools from the same household at the same time.
Read more on that in the
Pokerfuse iPoker split FAQ (it dates back to September 2012 so the list of iPoker2 skins is obsolete: Winner, Everest, Betfair, Coral and Gala have joined since then.)
Betfair were included into iPoker2 immediately when entering the network on January 21st. Existing customers were allowed to play on Ongame too until July, but new signups have been able to play only on iPoker ever since.