I don't know how GL SDK and Apple TV communicate, but maybe due to redundant discovery protocols or so. Many protocols and multiple ports are involved for "Samba" sharing. e.g., mDNS, SSDP, WINS, SMB, CIFS, etc... So several scenarios are possible.
Whatever the cause, both will connect to the same destination. Just consider them as two identical shortcuts.
Probably you won't get some clear response from either GL.iNet or Apple, but if you're curious, try investigate with Wireshark or so.