If somehow I cast multiple copies of Beacon of Tomorrows at once or in the same turn, will I get all of the turns back to back? Or, because of it's wording, would all of the extra turns happen in the exact same point of time?
You will get it back to back. See Comprehensive Rules.
500.7. Some effects can give a player extra turns. They do this by adding the turns directly after the specified turn. If a player is given multiple extra turns, the extra turns are added one at a time. If multiple players are given extra turns, the extra turns are added one at a time, in APNAP order (see rule 101.4). The most recently created turn will be taken first.