The only ways the system will let you do it...
1) if the meals are booked far enough apart time wise so that it's not considered a double booking (I can't remember but this may be a 2 hr window- maybe someone else can confirm the specific parameters). You can always experiement with this on their website before your 180 day hits.
2) you book under totally different information for that second adr. i.e. different phone, name, email, etc. If you like to look at all of the reservations on your account when logging into the Disney website, this information will not be visible as it's a double booking and the system won't support that.
This policy is enforced on all adrs, not just the cc guarantee ones. They also will not override this on the phones.
***An idea just since double bookings can hurt the system (i.e. make it hard for others to book and is not a proper reflection of availability- which could lead to increased costs) ... if one of those two meals is easier to book, you might make the adr for the more difficult of the two and then wait to see if you really need to change it to something else.
Example- we have one day where I'm really on the fence about our options. Le Cellier lunch would be the most difficult of the bunch to book, so that's what I'm booking on day 180. I know the other three options are easier to book, so rather than create a double booking situation- I'm just going to wait until we're closer to our travel time to decide if we want to swap out this adr.