Lindsay Arnold and Witney Carson have a lot in common.

They're both 18-year-old blond ballroom dancers who just graduated from Utah County high schools (Arnold from Timpview; Carson from American Fork).

Both are the oldest of four children. Both dance at The Vibe studio in Pleasant Grove. Both auditioned for "So You Think You Can Dance" in Salt Lake City in February. Both were convinced that only one of them would make the top 20.

And both were wrong. Both Arnold and Carson made the finals of the Fox TV dancing competition — although the judges stressed them out a bit by making them think that Carson was in and Arnold was out.

"That was so hard — having them tell me I made it without telling her," Carson said. "It was so heart-wrenching."

"I honestly felt like they were going to pick one of us," Arnold said. "So when they told me that she made it and I thought I hadn't, I really wasn't surprised. It was crazy when they actually let both of us on the show."

It's not so unusual to have two or more Utahns on "SYTYCD." It's happened before. Three times.

This year, Utah can claim three. Nick Bloxsom-Carter is a Utah Valley University student from California who is — you guessed it! — a ballroom dancer who trains at The Vibe.

What makes Arnold and Carson's story unusual is that they've been friends since they were little girls, competing across the country.

"Dancing with Witney has been fun," Arnold said. "We've grown a really strong friendship. We compete against each other, but it's been healthy for us. We've never gotten competitive with each other."

Which made it a bonus when they got to the Las Vegas round of the auditions and discovered they'd been assigned as roommates.

"Having Lindsay around made it 10 times easier," Carson said. "We're so comfortable with each other. We just support each other through everything."

Both teens are big "SYTYCD" fans who have watched the show for years. Both were just waiting to turn 18 to audition. And both are beyond excited to have made it to the top 20.

"I can hardly believe it," Carson said.

"I'm kind of shocked," Arnold said. "And I never thought it would be both of us.

The two have one more thing in common. As the competition resumes on Wednesday (7 p.m., Fox/Channel 13), neither of them is exactly anxious to strut her hip-hop skills.

"Hip-hop intimidates me," Carson said. "I's completely opposite from ballroom."

"I'm just worried that I'm going to get some really hardcore hip-hop and I'm not going to be able to handle it," Arnold said.

So far, they've both handled everything just fine.

Scott D. Pierce covers television for The Salt Lake Tribune. Email him at spierce@sltrib.com; follow him on Twitter @ScottDPierce.