That is because its a vendor logo stored in another area of the flash that is not written over when flashing a image.
You need to have the splash_cfe_auto.bin file for the openpli image and flash it like a image just this file and it will over write the previous one and wont affect your image.
Its flashed like an image just unrar and place the attached into a empty folder system for flashing only file in that folder system should be the splash_cfe_auto.bin file