This is true. There is logic built within the FICO credit scoring system that treats multiple mortgage and auto inquiries as one search for credit (a.k.a. only one hard inquiry).
The goal of this logic is to prevent consumers from being penalized for being aggressive interest rate shoppers and only count the fact that they’re looking for one loan against them. The alternative is to have their scores negatively impacted for each and every individual inquiry.
Some of the versions of the FICO scoring credit-scoring models group inquiries into 14-day increments while others group them into 45-day increments. However, since you don’t know which version of the score you’re being scored with, it's best to do all of your shopping within a 14-day window.