Can I use the same credit-card for two (2) different plans?
Yes.
The same credit-card may be used for two (2) different accounts however there is a waiting period before the system will accept. The system and our processor-partner both perform initial checks when a credit-card is entered. Typically the wait period is one (1) hour.
note: the waiting period is for any two exact charges to the same credit-card (and varies per payment processor). If the plans are at different prices then there would not be a waiting period.