I think walang difference. PLDT logo si RP2646 while generic logo si RP2646.
Pang AN5506-04-FA (hardware version WKE2.134.285F1A). Anyways, chin check ng modem kung compatible ba ang hardware version sa header ng BIN file bago niya i-flash.
Try this.
Download and then unzip to a USB drive formatted to FAT32. Plug it into USB1 of the AN5506-04 and reboot. Wait for all LED to light up and unplug. This will update the firmware to RP2647 (Brazil)
https://drive.google.com/file/d/1qv2dh6MzsYfeBrswh104Nb4AfWBOukya/view?usp=sharing