Why The Triwizard cup Portkey worked twice

 Welcome back to me getting pressed on about flaws in a fictional universe. Today, I'll be ✨explaining✨ why the Triwizard Cup in the 4th book worked as a Portkey two times. 

So, after Harry and Cedric touched the Triwizard Cup together, they were both transported to the graveyard where Voldemort's father (a muggle) was buried. After Wormtail got rid of Cedric, he revived Voldemort. Then of course Harry and Voldemort dueled, Harry got away, and touched the Portkey to go back to Hogwarts. But, here're 2 things which have always bothered me. 

1. How did the Portkey work twice? Every other example in the books shows them working only once.

2. How did the Portkey transport Harry to the entrance of the maze, and not the center, where it was originally placed? 

Portkeys are supposed to work one way right? In Quidditch Through the Ages, we see an example of a Quidditch foul, which involved turning the broom of the referee into a Portkey, which caused him to turn up in the Sahara Desert months later. This means that the broom Portkey couldn't transport him back, hence it didn't work twice. So, what went wrong with the Triwizard Cup Portkey?

Nothing, in fact, went wrong. I believe that the Cup was charmed twice by both Dumbledore and Barty Crouch Jr. (impostor Moody) on purpose. Okay, of COURSE Barty charmed the Cup to reach the graveyard, but why did Dumbledore charm it too; that's sus. 

I think Dumbledore made the Cup a Portkey which would transport the Champion to the entrance of the maze. Think about it, it would suck for someone to find a way back to the entrance after winning, so Dumbledore simply made the Cup into a Portkey! Bart Crouch Jr. wouldn't have cared if he knew about it, because Harry was supposed to die in the graveyard anyway. 

I believe that Dumbledore charmed the Cup first, and the Crouch Jr. charmed it next after he placed it in the maze. The charm placed on top of Dumbledore's worked first.

Now that I think about it, I put too much thought into something that's supposed to be fictional. I should really get going with my homework due today, but this is much more important; am I right, or am I right?