Thanks for your attention!
I imported a svg image, extruded it, did the shortcut 'I' thingy. Now I have those overlapping faces in corners.
I tried 'remove doubles' but it didn't remove any verticles(tried merge distance as well). Merge didn't do the job properly either.
How may I handle this? I want to extrude the inner face after organize the border part faces.
It would be lovely to have some advice long or short! Thank you in advance. Wish you a lucky day :)