What is the meaning of the phrase "So-and-so narrated to us, so-and-so narrated to us" that appears in the chains of transmission (isnad) of hadiths?

The meaning of their saying: "thana fulan, thana fulan" is "haddathana fulan, haddathana fulan." Al-Suyuti mentioned in Tadrib al-Rawi that abbreviating "haddathana" to "thana" and "akhbarana" to "ana" was common due to their frequent repetition. The letter "tha" might also be omitted from "thana," and only the pronoun "na" would be used.