OK, I was quite missing the point. It's an expression for "tare AND sauce", and I see it's often part of たれ・ソース・ドレッシング. I've been misled before by ・ being both a word separator in 外来語 and the separator for lists of words.
Perhaps for the benefit of people like me it should stay as "(exp,n) tare and sauce", but I really wouldn't object now if it went.

But "たれ・ソース" is not a different way of writing たれソース but in these cases the same as saying "たれ＆ソース". E.g. 
https://www.amazon.co.jp/たれ・ソースの基本とア�%
83%AC%E3%83%B3%E3%82%B8571-%E5%AD%A6%E7%A0%94%E3%83%91%E3%83%96%E3%83%AA%E3%83%83%E3%82%B7%E3%83%B3%E3%82%B0/dp/4058003944
"たれ・ソースの基本とアレンジ571"
This isn't a recipe book containing 571 recipes for "tare sauce", it's 571 recipes for various sauces, including dipping sauces 
(and other soy/mirin-based sauces that might be called "tare" rather than "sauce" in Japanese).
I don't think this appears on packages, at least I've never seen it, and again, there's nothing on Google images.

たれソース	1451
タレソース	153
たれ・ソース	15192
タレ・ソース	850

Yes, it's almost always "たれ・ソース", but that shouldn't eliminate it. Quite tautological as I commented earlier. If someone sees a packet in a shop they should be able to look up たれ・ソース.

@@ -18 +18 @@
-<xref type="see" seq="1370860">垂れ・2</xref>
+<xref type="see" seq="1370860">垂れ・1</xref>

Same for Google Images. I suggest deletion.