Why does when my hdmi cable go into my ps3 i put it on 1080 i or 720p my pictures doubled?

You have to tell the PS3 you have a new cable. Start the PS3 on the on switch on the unit. Keep it pressed untill you hear a beep. It will then ask you wich resolutions your TV is capable of handling and then use the highest possible (Which is 1080p on HDMI if your TV supports that).