WATCH: Will Ian McKellen Marry Derek Jacobi?

Ian McKellen and Derek Jacobi are both acclaimed British actors, are both gay, and have both received knighthoods -- but they're not interchangeable, nor are they engaged, as a confused Thomas Roberts thought Friday.

The out MSNBC anchor spoke by phone with the two actors, who were in a car in New York City, where they will be among the grand marshals of the Pride parade Sunday. They first discussed the Supreme Court marriage equality ruling, with McKellen telling Roberts that on Pride weekend in New York, "there are going to be an awful lot of men kneeling in front of other men saying, 'Please, will you marry me,' and women doing the same thing."

Then Jacobi got on and discussed the importance of marriage equality and his own plans to marry, after which Roberts asked him, "When do you return as Magneto in X-Men?" He replied with a laugh, "I don't play Magneto in X-Men. That is Ian McKellen. You're actually talking to Derek Jacobi."

When McKellen got back on the phone, Roberts said, "I was speaking to your fiance. I thought I was speaking to you." Soon, McKellen clarified, "He's not my fiance, but would he were. ... Derek and I work in a wonderful show called Vicious, which is about two old gay men living in London for the last 50 years."

Roberts took it in apparent good humor. Perhaps he was confused by an adorable BuzzFeed video in which Jacobi proposed to McKellen, but in reality, Jacobi is in a civil partnership with actor Richard Clifford, and they plan to be married soon. England has had marriage equality for a few years.

Watch Roberts's report plus a couple of celebratory McKellen-Jacobi BuzzFeed videos below.