CUAV C-RTK 9P DUAL

Hello
I’m using pixhawk cube black.
I connected two CUAV C-RTK 9P to pixhawk’s GPS1 and GPS2.
I checked the 3D FIX in the mission planner. However, the GPS2 has a HDOP of 99.
Is it normal? If not, what should I do?
Please help me. Thank you.