Choice of GPL versions 2 or 3 reported as gpl-3.0

The source files for https://www.remlab.net/ndisc6/ have the following license notice:

5 /*************************************************************************
6 * Copyright © 2004-2007 Rémi Denis-Courmont. *
7 * This program is free software: you can redistribute and/or modify *
8 * it under the terms of the GNU General Public License as published by *
9 * the Free Software Foundation, versions 2 or 3 of the license. *
10 * *
11 * This program is distributed in the hope that it will be useful, *
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
14 * GNU General Public License for more details. *
15 * *
16 * You should have received a copy of the GNU General Public License *
17 * along with this program. If not, see . *
18 *************************************************************************/

SCTK 30.1.0 reports this as gpl-3.0 with a score of 97.87