There is a couple of issues with additional date fields.
1. In some situations (which I can not yet define) when you insert a new date into a date field, it always reverts to 01.01.1970 and you cannot change it no matter what. 2. While editing date fields, when you press and hold ">>" the years that show in the drop down menu depend on the year you are currently on, with one peculiarity: if the year you are currently on is even, the drop down shows only odd years; if the year you are currently on is odd, the drop down shows only even years.
I have attached a file to illustrate this.
These annoying bugs seem to be happening a lot lately. Maybe you should take a look at your QA process.