Yes, only one PCH. The seconds (higher) value is the internal temperature, the other one most probably a diode close to the PCH placed by the mainboard manufacturer.
I also have 2 Chipset temp readings on my board in HWiNFO‘s sensors with ~20C difference. In BIOS’s smartFan section there is only one reading about PCH and it matches the lower one. I also confirm it with board software by vendor (Gigabyte) that the reading in BIOS and the lower one in HWiNFO is actual what the board “sees” as PCH temp.
I read on another Tech forum that the other (higher) reading could be some voltage regulator of chipset power rail(s) but this I cannot confirm.