Passports and Entry Through Customs Controls Are Required

Passports and Entry Through Customs Controls Are Required To Legally Travel To Planet Earth.

See: Different Writing Systems Are Used On This Planet Than The Original Ones, Unaffiliated Instances Of The Same Planet  

 Societies with writing systems too different for each other's citizens to fluently read would be unlikely to be conjoined even if they seemed like multiple instances of the same planet.

If criminals were or are in control of other instances of this planet and could claim affiliation of their society with ours, they could claim that their local laws and regulations applied to this instance of the planet.