This appears to differ from the MISRA C 2012 interpretation. Rule 8.5For the purposes of this standard, in headline rule text a
declaration is the first introduction of a name into a translation
unit. All subsequent â€œdeclarationsâ€ (as per ISO/IEC 14882:2003 
Â§3.2(1)) are re-declarations.
includes the text:
According to the MISRA C++ glossary entry, the use of "once" in the headline... shall be declared once in one and only one file.
text is redundant, as any additional declarations are "re-declarations".
Is the MISRA C meaning intended to be different to that of MISRA C++ 2008?
If so, could you provide an example where it is dangerous to use re-declarations?