The F-line trap error is probably spurious. You just plain ran out of memory or overflowed something, and the garbage instruction it landed on was an Fxxx instruction. Even if it did have an FPU, it would still have crashed, just somewhere else.

Someone else can comment on the copy (I suspect it is a swap for each fork), but the icons probably come down to type/creator codes. Assuming there is no custom icon resource, the Mac will try to harmonize two files with the same type/creator to the same icon. This can appear non-deterministic depending on what applications are installed and their state.