Jelly, 8 bytes

³X’+ƲƬI;

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Jelly, 8 bytes

³X’+ƲƬI;

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Explanation

³X’+ƲƬI;   Main niladic link
     Ƭ     Repeat and collect results until there's a duplicate result
    Ʋ      (
³            100
 X           Choose a random number from 1 to 100
  ’          Decrement (to get a number from 0 to 99)
   +         Add to the current value
    Ʋ      )
      I    Increments (deltas)
       ;   Join with the implicit argument, 0