The tension, or force needed for the 'pull' is evenly divided between the number of lines. So if the is a single pulley at the other end, and 2 (duplicate) lines, then each line will tension to EXACTLY half the total force, however the pull distance that YOU exert will be twice the distance the 'object' is moved.
If there is a double pulley at one end, single at the other for a total of 4 lines, then the winch force required to move the object would be one quarter the total force necessary to move the object, however the winch distance is 4x as much as a straight pull...
Double pulleys at both end; winch force is one fifth of the total 'pull'
There is no free lunch...the work required is always the same;
1 pull over 1 distance
half pull over twice distance.... etc