Warnings from make

[Christer Solskogen]

While building glibc I get this:
../Rules:222: target 
'/tmp/build.s390x/glibc.full/localedata/tst-langinfo-newlocale-static' 
given more than once in the same rule
../Rules:222: target 
'/tmp/build.s390x/glibc.full/localedata/tst-langinfo-setlocale-static' 
given more than once in the same rule
../Rules:222: target '/tmp/build.s390x/glibc.full/elf/tst-tls1-static' 
given more than once in the same rule
../Rules:222: target '/tmp/build.s390x/glibc.full/elf/tst-tls2-static' 
given more than once in the same rule
../Rules:222: target 
'/tmp/build.s390x/glibc.full/elf/tst-ptrguard1-static' given more than 
once in the same rule
../Rules:222: target 
'/tmp/build.s390x/glibc.full/elf/tst-stackguard1-static' given more than 
once in the same rule
../Rules:222: target 
'/tmp/build.s390x/glibc.full/elf/tst-tls1-static-non-pie' given more 
than once in the same rule
../Rules:222: target 
'/tmp/build.s390x/glibc.full/elf/tst-libc_dlvsym-static' given more than 
once in the same rule

(I get this warning a couple of times during 'make')

[solskogen@manjaro-builder glibc.full]$ make -v
GNU Make 4.3
Built for x86_64-pc-linux-gnu
Copyright (C) 1988-2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Is this a problem? A problem on my side or perhaps a bug that needs 
reporting?