Users voting and removing their votes corrupt voting percentage statistics

[Hibbelharry]

If a user votes for an issue and removes his vote again, percentage statistics for votes get wrong since a vote is never subtracted from the count of votes. If a user does this repeatedly and abuses the mechanisms in that way, voting percentage statistics might loose all statistical value.

[ande3577]

The challenge is how to define treating a downvote from a user whose already upvoted. There are two conflicting use cases

1. The downvote is intended to cancel out an earlier up vote. In this case, the earlier vote should be subtracted from the total.
2. Up/downvotes are used to treat the rate of failure of an issue. (eg on one run 90 we successful and 10 failed). In this second case the votes are second occurrences which should be added to the percentage/count.

The challenge is either eliminating one use case or finding a way to implement both.

[Hibbelharry]

Current permission settings allow setting if a user is able to downvote on an issue. When we don't allow downvoting for an user i think we can be sure that a user is canceling his vote and the vote should be subtracted.

If a user is allowed to downvote an Issue, but not allowed for multiple votes, he would vote down two times if he voted up before. So the first vote is canceling his previous vote and the second vote is voting the issue down which should be added.
If a user is allowed to vote down and also allowed to multi vote on an issue situation isn't as clear for me. I would propose to use the same behaviour and teh difference from zero votes in either direction should be the resulting count of votes for a specific issue for a specific user.