Does "double RC4" exhibit the same weaknesses as standard RC4? I know that RC4 is weak.  However, I don't know if two RC4 streams XORed with each other can be attacked in the same way that one can, especially if $n$ bytes are dropped.

Assume keys and IVs are independent and random.

(This is purely theoretical, I don't plan on using it in practice).
It can be attacked in the same way, but not as efficiently.

The RC4 "NOMORE" attack (pdf), for example, uses both Fluhrer-McGrew biases, which are biases towards certain pairs of values in certain positions, and Mantin's "ABSAB biases", which are repetitions of bigrams. Both of those biases will survive a XOR of two keystreams, but will be less frequent.

A rough estimate would be that you need quadratically as much ciphertext, so that you can attack first one layer and then the next. That would imply  >$2^{55}$ captures instead of the ~$2^{28}$ in the attack demonstration, which would likely be too much to use in practice. However, depending on whether or not the two keystreams are aligned, that could be an overestimate or an underestimate.

It seems possible that a XOR of two independent RC4 keystreams would be too strong to practically break in such a manner, even if it was significantly below the strength implied by key size. However, distinguishing attacks require less data and are more likely to be feasible. (The attack in question decrypts cookies or other suitable data.)