As Pierre said: DCS is a variation on the Encapsulated PostScript. DCS stands for Desktop Color Separation.
If you want to be able to edit the plates separately, you can use Image>Mode>Multichannel. This will split your duotone into channels. This way you have the option to tweak each one separately. But you can only save as a psd, or a DCS.
If you want to save simply as eps (besides psd there is no other option for duo, tri and quadtones), you may want to do the following:
An eps has two parts: the postscript, and the preview. I f you choose tiff 1 bit, you get a black and white preview. For a coloured one, choose tif 8bit. Normally for quark you can use the Huffman encoding, aka Binary. But ASCII is more generally accepted, though much longer and fatter as everything has to be described.
Normally I let the printer do the screening, so I don't include a halftone screen.
Transfer function is better left alone.
ColorManagement is only ok for Postscript2 printers and above.
If you used vector data, check the vector box. If not, uncheck.
ImageInterpolation is only useful when you intend to change the format later.
And err...never mind if they have problems, ans Postscript is always the source of trouble in the printer world. That's why more and more printers move to Acrobat's PDF.
There are only two problems between pc and mac: the first are fonts, ie people coming with their layout made in MSWord to a mac oriented printer.
The second one is that mac uses headers. So postscripts coming from mac are often problematic on pc. When you get one and can't open it, throw it not in the dustbin but in the word-processor as PostScript is plain text. Then look for %!PS. What comes before this is the header and is unnecessary, so it can be thrown away.
And please: never let yourself be influenced by the so-called necessity for mac in the print world. I work solely on PC and they don't ever notice. Mac is of course very good, but pc is of the same quality, and the difference is like the difference between English and American. Lawyers and Bannisters, goals and jails you know,...
good luck!
need serious direction forsaving PC photoshop file for Quark 
Linear Mode
