pity that you bought them in the same week, otherwise we could find out who contributes what. It is obvious, you must sell one of them and then tell us :-)
merchandise is more long term, so he won't get a single race in the next week but he get several races over the next 4-5 weeks in income. So the problem isn't the same week, maybe more the same month ;)
Are you really sure about that?
My experience(and others) on this matter tells me that roster variations hits merchandising witihin one week of diference. Or, simply in the next economic update.
Later on, the effect is pretty small (less than 1% over the initial variation and presumible due to other aspects of performance).
That being said, there seems to be an incremetal patter on merchandising over the final weeks of the regular season. But this proposition needs to be tested on "unseccessful" teams(5th place or lower) who may be getting just the opposite (somebody here with a 0-18 or similar this seasson?)