All right, I called up Maybank Customer Care Centre for further clarification and found out that the credit lkimit is "shared", which means they have retained my credit limit, not per card but for two cards. 

These cards are not replacements for my VISA Petronas Card. So it means that they did double my credit limit. 

However, since I cancelled my VISA Petronas Card, I am back to the same credit limit. 

 I was asked why I wished to cancel my Petronas card... will would I want to hold TWO Visa cards? One is good enough. 

But then this means that I have to start from Month 0, and pay my credit card bills on time in order to enjoy the low 8.88% finance charge. 

Also, I found out that not all merchants are willing to accept AMEX cards because of higher transaction fee. So it IS difficult to collect 5X Treat Points or enjoy the cash back of 5%!