an.tmac, .TH: shows the same text twice in the header! Why necessary?

[Bjarni Ingi Gislason]

Example from "sensible-terminal(1)":

.\" -*- nroff -*-
.TH SENSIBLE-TERMINAL-EMULATOR 1 "28 Aug 2022" "Debian"
.SH NAME
sensible-terminal-emulator \- sensible terminal emulator

-.-.

With "/usr/bin/man --version": man 2.11.2

Output from "env MANWIDTH=80 /usr/bin/man -l example":

grotty:<standard input>:(<standard input>):9: warning: unrecognized X command 
'sgr 0' ignored
SENSIBLE-TERMINAL-EMULATOR(1General Commands ManuSENSIBLE-TERMINAL-EMULATOR(1)

NAME
       sensible-terminal-emulator - sensible terminal emulator

Debian                            28 Aug 2022    SENSIBLE-TERMINAL-EMULATOR(1)

-.-.

  The text "SENSIBLE-TERMINAL-EMULATOR" is output twice in the header,
is once not enough and why?  (Is this necessary(?))