CSS 2 validator passed overlapping definitions

Hi.. Please forgive me as I am new this week to learning and validating CSS & 
XHTML. I am passing on an observation from a CSS validation I performed this 
morning.

In creating one of my CSS's, I left out the property "color" when I put 
"background-color" for my div. I understood the warning I received, and I 
attempted to correct my oversight. In doing so, I accidentally placed two 
"background-color" properties on the same element. This in part is what the 
validator passed:

background-color:#FFF;
background-color:transparent;
color:#000;

The validator did not catch my mistake when I performed my final test on my 
CSS. It said I passed with no errors or warnings and displayed everything 
including both "background-color" entries on each element in question. I 
ended up accidentally catching this glitch when my page didn't display 
correctly in IE.

Again, this is just an observation. Being brand new, I am not up to speed on 
what does and does not matter with the validators and parsing. I thought I'd 
pass on what happened to me in case you all were interested in hearing that 
it could happen.

I joined the mailing list, and I'm looking forward to seeing what you all are 
up to on here.

Until then, have a great day!

Cindy Sue
FavoriteWebsite Guru

PS Who do I type at if I ran into a problem with joining the list? It won't 
accept the address I really need to use, and I haven't found any references 
regarding same anywhere on the site. Thanks in advance!