Master Yi and the longest living bug in the game

Hi everyone,

Ok, so I've got thousands of games on since season 2 (yes, another no-lifer). Although this bug isn't something I as a Yi player want Rito to change cus it's OP, I don't see this as fair. And this can't be intentionally done. Master Yi's passive reads as follows:

"INNATE: With every fourth basic attack (within 4 seconds of each other), Master Yi strikes twice, the second strike dealing 50% AD Attack damage physical damage. The second strike applies on-hit effects and can Critical strike icon critically strike dealing 50% AD Attack damage bonus physical damage. If Master Yi's primary target is killed before the second strike, he automatically attacks another enemy within 300 range."

Now, Master Yi's 4th basic attack does doublestrike, however, after his first 3 basic attacks he doublestrikes on the 4th basic attack. But after the initial 4th attack, he now doublestrikes on every 3rd attack after that. It's as if the last hit of the doublestrike counts as the first basic attack on the following attack sequence. This shouldn't be the case though, therefore I believe this is a bug Rito probably knew about but just let go. Combined with his doublestrike is now every 2nd attack, after the initial 3. I love playing Yi cus my mechanics are shit, but I think Yi is OP enough without this bug. And yes, it has to be a bug.