Paying less interest rate in credit card

Paying less interest rate in credit card

I think I've found a way to pay off my credit cards faster, and therefore
paying less interest rate. There's a Google Spreadsheet with my work at
http://goo.gl/NqliZM
My question
What payment strategy will save me the most money? From my spreadsheet, I
believe my idea actually works (saves me money), but is this reasoning
actually correct?
Explanation
My scenario is this: I have 2 credit cards, both maxed out at \$5000.
Credit card A has an interest rate of 10%, and card B has a rate of 20%. I
have unlimited and free balance transfers from card B into card A. So my
idea is this:
I only have a fixed \$300 to put on these cards every month. I could
either pay \$150 on each card, or pay \$300 on card A, then transfer \$300
from card B into card A. I've checked with my bank, and they assured me I
can in fact do this if I so choose.
My conclusion
Based on the results from my spreadsheet, I'd end up paying about 33% less
interest total (\$2,145.71 vs \$3,180.98) if I use the strategy where I
pay the entire \$300 on one card, then transfer that amount onto the other
card. Can someone with more experience verify that this is in fact
correct?
Edit
By transferring from card B to A I mean doing a credit card balance
transfer. Meaning bank A cuts me a check, which they take from my credit
line, then I pay that check to bank B, which lowers my debt with them.