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In Back to the future 2Back to the Future 2, old Biff stolenstole the time machine in 2015 and went back in time to give an Almanac to young Biff. At the point of giving the Almanac to young Biff in 1955, he altered the future making current reality to flow in another timeline (with bad future & bad 2015). So, how could he return to good 2015 of the previous timeline?
Plus, when our heroes returned back to 1985, how could they go into the bad timeline?

In Back to the future 2, old Biff stolen time machine in 2015 to give Almanac to young Biff. At the point of giving Almanac to young Biff in 1955, he altered future making current reality to flow in another timeline (with bad future & bad 2015). So, how could he return to good 2015 of previous timeline?
Plus, when our heroes returned back to 1985, how could they go in bad timeline?

In Back to the Future 2, old Biff stole the time machine in 2015 and went back in time to give an Almanac to young Biff. At the point of giving the Almanac to young Biff in 1955, he altered the future making current reality flow in another timeline (with bad future & bad 2015). So, how could he return to good 2015 of the previous timeline?
Plus, when our heroes returned back to 1985, how could they go to the bad timeline?

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In Back to the future 2, old Biff stolen time machine in 2015 to give Almanac to young Biff. At the point of giving Almanac to young Biff in 1955, he altered future making current reality to flow in another timeline (with bad future & bad 2015). So, how could he return to good 2015 of previous timeline?
Plus, when our heroes returned back to 1985, how could they go in bad timeline?
The doc is explaining alternate timeline

In Back to the future 2, old Biff stolen time machine in 2015 to give Almanac to young Biff. At the point of giving Almanac to young Biff in 1955, he altered future making current reality to flow in another timeline (with bad future & bad 2015). So, how could he return to good 2015 of previous timeline?
Plus, when our heroes returned back to 1985, how could they go in bad timeline?
The doc is explaining alternate timeline

In Back to the future 2, old Biff stolen time machine in 2015 to give Almanac to young Biff. At the point of giving Almanac to young Biff in 1955, he altered future making current reality to flow in another timeline (with bad future & bad 2015). So, how could he return to good 2015 of previous timeline?
Plus, when our heroes returned back to 1985, how could they go in bad timeline?

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