When Barbara Corcoran walks into a business and gives her name, she can see the disappointment on people’s faces immediately.

“I went into a rental car place in Cooperstown and said, ‘Hi, I’m Barbara Corcoran,’ and I could see [the employee] literally deflate in front of me,” Corcoran told The Post. “This kind of thing happens at least once a year.”

Barbara Corcoran, 60, is a Realtor and luxury property specialist at William Raveis’s Osterville office on Cape Cod in Massachusetts. She’s been in the real estate business for about 20 years and has sold more than $100 million worth of property.

Corcoran has been her married name for more than three decades. She and her family, however, are not related to “Shark Tank” star Barbara Corcoran, 77, who famously sold the real estate firm she founded, the Corcoran Group, for $66 million in 2001.

But despite being a mom of three from a different state, working in real estate under the same name as, arguably, the most famous broker ever, Corcoran is used to being mistaken for the New York real estate maven.

“When I was working at my first company, I received a phone call from a gentleman asking me to speak at a real estate conference, but I had only been in the business two years and had no idea why he’d ask me,” Corcoran said. “But he didn’t want me to speak, and that was the first time it clicked.”

Corcoran said that when she started in real estate 20 years ago, the other Barbara Corcoran wasn’t on television every week through ABC’s “Shark Tank” — which premiered in 2009 — or all over social media, where she now has 1.3 million followers on Instagram and TikTok each.

Now, Cape Cod Corcoran said she can’t Google herself or promote her business online without having to go through “pages and pages” before she can find herself on the screen.

“One time, [a receptionist] told me that she got up early and put on all of her makeup and got all ready because she thought she was meeting Barbara Corcoran,” she said. “And she did meet Barbara Corcoran! Just not the one she thought.”

There have also been errant emails.

“[Years ago], I received a receipt from Vineyard Vines to my generic ‘bcorcoran’ email,” Corcoran added. “I opened it up, and the clothes purchased were all a size 2! I’m not a size 2. So I was like, ‘Yeah, this isn’t me.’ And then wondered if this was her order.”

New York’s Barbara Corcoran, who is renovating her newly purchased $16 million Carnegie Hill penthouse, could not confirm the years-ago clothing shopping spree, but was delighted to hear another Barbara Corcoran was working in real estate.

“I’ve always said there’s only one Barbara Corcoran — but it sounds like I may have some competition!” Corcoran told The Post. “Any woman who’s built a 20-year career in real estate while raising three kids already has my respect.”

“If she’s getting my speaking invites, I hope she’s charging more than I did starting out,” Corcoran quipped.

And there could be more cases of mistaken identity in the future: An affiliate of the Corcoran Group, Corcoran Property Advisors, opened its first Cape Cod office in February in Osterville, the same town where Corcoran’s William Raveis office is located.

Meanwhile, Corcoran is holding on to hope that one day she’ll meet her name twin.

“I’ll make jokes like, ‘I am so sick of her taking my name,’” Corcoran quipped. “Like, who does she think she is? So, I turned it around. My social media is ‘the other Barbara Corcoran.’ I’m still hoping to meet.”