Clash of clans gamecenter conflict?

so my dad gave me his iPhone 4, and stuff, so i signed out of all his things and into mine, and then i downloaded clash of clans. He had already played a little on the iphone 4, and he gave this one to me because he has an iphone 5 now, and plays on that. I have also played a little on a different iPad too. So i opened CoC, and then i could see my dad's town in the background and this message came up: "Do you want to load Chief DBweasel's (my username) village with town hall level 6? Warning: progress in the current game will be lost." i havent clicked okay, because im not sure if that would get rid of his progress on all devices or not. I just want to check my town without All his progress gone. Like i said he still plays on the same town on his new iphone, and he has a really good town that he would FLIP OUT if his progress got deleted. So i just want to know if All his progress would be gone or if it would just let me view my town on my iphone that he gave me.

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