Toilet flushing twice

I have a Gerber toilet in my downstairs bathroom that flushes twice every time I flush it. The bowl empties, refills, empties again, and then refills again. I believe it is the original toilet from when the house was built in the early nineties. Any suggestions on a possible fix for this? The toilet has no other problems so I don't want to shell out the cash to replace it. I just don't like paying for water that I'm not using. Thanks!

You may have replaced the flapper valve with a generic, and it is staying open too long, providing enough water so it has to flush twice. Most toilets today shut the flapper fairly quickly and don't empty the tank when you flush. you need the correct flapper vavle to do that. Some use floats, some use strategically placed holes and maybe a combination of the two.

toilet

And some toilets flush better with the double flush.