Tests the effect of ordering and activating two sync_bill_date packages on the same day. Ref RT#42108.
Formerly correct: If the packages have prorate_round_day = 1 (round nearest), or 3 (round down) then the second package should be prorated one day short. If they have prorate_round_day = 2 (round up), they should be billed for the same amount. In both cases they should have the same next bill date.
Revised RT#72928: The second package should be prorated one day short only if the rounding mode is 1 (round nearest), as the nearest day is different for the two packages.