libpng changes over the years

see https://gitlab.com/fedora/legal/fedora-license-data/-/issues/296

http://www.libpng.org/pub/png/src/libpng-LICENSE.txt is the URL for both libpng-2.0 and Libpng

the first part/license:

is a match to libpng-2.0 (and this is the URL is referenced in the SPDX entry) which was added for version 3.5 in 2019

the second part/license:

SPDX added https://spdx.org/licenses/Libpng.html in 2010 for version 1.4 of the SPDX License List (see https://lists.spdx.org/g/spdx/message/236?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Acreated%2C%2Clibpng%2C20%2C2%2C0%2C22079229
discussion of this at https://lists.spdx.org/g/spdx/topic/22079227#msg235
SPDX added what existed on that same URL at that point in time. See https://web.archive.org/web/20101202114005/http://www.libpng.org/pub/png/src/libpng-LICENSE.txt

BUT over the years, various things were updated such as the list of names and references to version numbers (which would be replaceable by SPDX matching guidelines, but need markup added) More substantial text changes occurred as well:

libpng-2.0 was added in Nov 2018, which also altered some of the text order, see https://github.com/pnggroup/libpng/commit/e79085a1724ccc5526dc752f6a696b3a94ef8cfa

question is for SPDX now: should these various changes over the years be handled with markup or constitute a new license?

spdx / license-list-XML

libpng changes over the years #2591