Currently repairing my credit. Should I get a second credit card?

Brief summary: When I was younger I piled up about $6000 in CC debt. I just paid it all off over these past 2 months. 2 months ago, I applied for a Capital One Secure card and got accepted. I've paid off both balances so far.

The issue is, I know Cap One will never increase the credit limit on this secure card. And I know having a card that has the possibility of getting an increased limit can help push my credit score forward. So, should I apply for a second card that would offer a higher credit limit? Also, if I should, what card would you recommend? Thanks.