This is odd, because AFAIK the most common shorteners do not behave this way.
I have encountered shorteners in the past who would only count an ip once per 24h regardless who's shortlink was used.
But today, this is IMHO virtually  unheard of?
I'm seeing a lot of short link traffic with my sites and if an ip would only be counted once regardless of short link account, the statistics would look very very different.

P.S. Granted I work exclusively with dynamic links, which in my case results in each link only existsing once and once visited it's gone.