I don't know.
Probably ARC1 doesn't know that ARC0 is doing this log until it's finished, and just tries.
But it looks stupid...

Everything I found on metalink was explanation, that one is manually issued with 'alter system archive log current'.
But in my case it wasn't it. Nor in yours, i guess.

I can't really remember now, if restarting just archiver helps, or database should be rebounced. Try.

Have fun,
Tomaz