One leg being stronger than the other is not something to cause that much consternation and not by itself even suggestive of a medical problem. Many people have a stronger arm and/or leg and it's primarily because one is dominant and is used more often or strenuously. Our work load between legs is necessarily not equal just because we stand on both legs.

My left leg is stronger - I have enough kinesthetic sense that I am certain of greater power from the left while cycling. When I had an injury to my right knee 5 or 6 years ago I still biked quite a bit and maybe 90% of my pedal stroke was from the left leg for perhaps a month. I'm sure that it strengthened my left leg during that time - which means that simply reversing it (in moderation) would strengthen the right leg comparatively. That's what I'm doing now (because I want more power, not that it's a "problem" that needs to be corrected). But I have to temper my expectations because looking back, one leg has always been dominant. Sprinting out of a track block, always the left leg. High jump and long jump, springing off the left. But sprints, cuts and jumps such as in football and basketball, neither leg was particularly favored. I think that beyond specific goals in weight-training and body-building, it may not be feasible nor worthwhile to try to train both sides to exactly the same strength and development.