You can use && to show one on the control.
Alternatively you can set UseMnemonic to false, then it treats & as a normal character, so only One needed.
According to documentations:
You may want to display ampersands in a label control, rather than use them to create access keys. This may occur if you bind a label control to a field in a recordset where the data includes ampersands. To display ampersands in a label control, set the UseMnemonic property to false. If you wish to display ampersands and also have an access key, set the UseMnemonic property to true and indicate the access key with one ampersand (&) and the ampersand to display with two ampersands.