Specialization is for Insects
I know, it’s a Heinlein quote.
A few years ago, I was in the same sort of position I’m in now. That is, looking for a full time gig to support the family. Need a PHP Programmer / System Administrator? 
Then, I split my resume into two parts- a “programmer” resume where I tried to speak more to people who wanted programmers, and an “administrator” resume where I did the same with more of an admin slant. This time around, I didn’t bother with that. I figured I’d put my cards on the table and play my strongest suits together- I’m good at both.
I’ve started asking “Why Me? Why did you pull my resume out of that stack of six thousand resumes to ask me to come in?” Because, let’s face it; the openings have a lot of applicants, and the hiring people have to choose on something.
The two people of whom I’ve asked this question have said the same thing; “your combination of PHP skills and your System Admin chops.” Well, not in those exact words, but pretty close.
So if you’re following the instructions of some resume writers, and focusing on one skill set for your job search, don’t be afraid to change it up a bit and lay your cards out too.