The cinematic universe of this world actually is two universes, collectively called the Diverse. The home universe has a few names that all mean the same thing: Olvonict, the Home Universe, the Uni, Homeverse, etc. Hammer, is really the only name for the other verse. Collectively, they are called: the Diverse, the verses, the multi, etc.
Portals across the verses do exist, but domestic (i.e. within the same verse) portals aren't possible. When crossing portals, your atoms are more prone to being dislodged, so going across two portals within a few days is likely a bad idea. It's a bit like decompression. The area around a portal is still affected by the other verse. For example, a hammerspace portal, where the area in Hammer still is much less affected by "decompression".
Portals are really only used for mid-sized ships, as making a big portal and keeping it open for a long time takes preposterous amounts of Zoran, and small ships are too small for it to be useful.