Cyrillic tverdo writes the same consonant from the same place and takes the same numeral, three hundred, which it inherits from Greek tau while Glagolitic reaches it by counting. The names are the same adverb with different vowels, and both recitations put it in the same position.
The pair sits at the boundary of the two halves of the Slavonic alphabet, and the halves behave differently. Before this point the names are ordinary words and the letters mostly answer to Greek letters. After it the names become opaque, the letters are increasingly Slavic signs with no Greek counterpart, and the numeral systems begin to come apart again after their brief agreement.
That structure is one of the strongest indications that both alphabets were arranged deliberately rather than accumulating. Someone laid the Greek order down first and then dealt with what Slavonic needed that Greek did not supply, and the second half of the alphabet is where the second job was done. It is also where the evidence is thinnest, because the letters there are rarer, their forms vary more between manuscripts, and their names cannot be etymologised. The atlas records the letters of that stretch with the same care as the rest and marks the gaps as gaps.