Not sure I understood you well. You applied for an extension in January, and it was approved till March, and in February you applied for another extension is that correct? I am assuming you asked for 6 months and hence the assumption that if approved it will end in August? Either way, you cannot apply for another extension before you receive the decision on the one that they are still processing. You have implied status until a decision is made on your application to extend stay
If the application is rejected you might end up having to apply for restoration.
If its approved, it will depend on how many days/months they approve it for.
Also depending on the visa officer, they might approve the extension giving you 6 months from when you submitted (February -august), or giving you 6 months from when it was approved (for instance July - Jan 2021).
So you really need to wait for the decision to know what your next steps will be.
If you have not yet submitted the PR application, you might want to consider which route is best for you. Just note that inland application makes you eligible for Open work permit