It has been known to happen that two male bettas will get along ok but it's always a risk. They may even get along for several weeks or months, and then one day one will challenge another over territory, food or whatever, and that will be the end of it. They may never fight, or you may find them one day torn up and one or both fatally injured. It is up to you if you feel the risk is worthwhile, but it is a gamble.