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Yes, both modules do different things, there’s no duplication.
But the improvement in main (rear) camera picture quality by this hardware upgrade is much smaller than the improvement from using a different camera app. Especially the (free) inofficial GCam app is our (i.e. the community’s) usual recommendation:
This is a very, very frequent discussion in this forum, so you might want to follow up in the topic above if you have questions regarding GCam.