truevalue and falsevalue of a checkbox

I have two checkboxes, in a winforms application. The truevalue and false value of checkbox are same.

After checking both boxes. When i uncheck the first box and then uncheck the second box, the first box gets automatically checked.

I then realized, that setting different values of truevalue and falsevalue of the checkbox resolved the error.

Now, my question is, why do same values cause this error.

I didn't add any code, becuase it wasn't needed.