parallel usb stick write error

[mreg]

windows 7 x64 pro
two different iso files on D:
insert 2 sticks
start 2 instances of unetbootin-windows-608.exe
on first start writing the iso number one to stick G:, it works
on second try to write iso number 2 to stick J:
error: "file exist, overwrite? C:\Users\me\AppData\Local\Temp\\7z.dll" exist, press yes, yes all, or no ...."
If pressed yes the program exit, and also for No exits.