Not really that surprising, accurate temp one is 2 degrees up the other 2 degrees down and you have 5 degrees in the difference. Unfortunate, I'd actually try to split the difference. Ironically the cheap liquid crystal stick on ones are usually more accurate (+/- 0.5ºF) than both they are cheap, just don't stick it on ( it will not be a good representation of what the rest of the enclosure is) use it where the probe is and check the T-Stat against it.