How much would this AES modification improve security?
It would not improve security at all.

For AES-CTR mode, encryption and decryption use the same algorithm: generate the key stream using the counter and then XOR the plaintext with it. Because of that, step 1 and 3 would completely cancel each other out, and you would be left with the "decryption" in step 2.

If you'd just use the first two steps then you would actually two independent keystreams. However, as they both rely on the AES algorithm then if the algorithm is broken, your scheme may still be broken as well. This is why usually that kind of construction is created with two algorithms that are rather distinct from each other.

You keep trying to "improve" a cryptographic primitive that is already considered secure. Why not try to improve one of the many problematic schemes? Preferably you would try and first understand the scheme before trying to improve it, like you tried to do for AES-CTR.