rule w/multiple targets causes failure in -j mode; how to fix

[Jamie Cuesta]

Running latest (2008/03) MinGW make.  Running make non-recursively with a 
single makefile.  Some rules are unavoidably multi-target, and they are thus 
because a single tool invocation generates multiple files, sometimes of 
different types/extensions (and this cannot be changed; in some cases the MIMO 
nature of the tool is a correct design; in other cases the tool is 
proprietary/unchangable; an example of the latter is a C compilation that 
results in a .o file and a .h file intended for use by asm source files).  

Anyway, running sequential-mode make succeeds, whereas running make -j leads to 
a failure when, for example, make attempts to run the rule twice simultaneously 
on the two targets in the multi-target rule.

I've searched the web and haven't found a gnu make specific solution to this 
problem; I find that clearmake and other makes offer a "target group" 
concept/feature (joining target list elements with '+') which seem to address 
this exact problem, but while I've seen 2 year old email threads discussing the 
possibility of implementing this feature in gnu make, the feature does not 
exist in the current gnu make, so there appears to be some bias against it.

What's the preferred way to overcome this problem?

TIA,  Jamie