bash-2.05b# make oldconfig
scripts/kconfig/conf -o arch/i386/Kconfig
file drivers/video/bootsplash/Kconfig already scanned?
make[1]: *** [oldconfig] Error 1
make: *** [oldconfig] Error 2

This error happen due to duplicate entry in the Kconfig file one level above the Kconfig file that reported in the error
For example from the error message above. Actually file
/usr/src/linux/drivers/video/Kconfig
is having duplicate entry:
if FB
source "drivers/video/bootsplash/Kconfig"
endif
if FB
source "drivers/video/bootsplash/Kconfig"
endif


This problem can be fixed by removing the duplicate entry in the file.
if FB
source "drivers/video/bootsplash/Kconfig"
endif