When you wish to quote from different sources, you need to either use a PM window, or a thread window...

With a thread window (like this one I'm typing in after another's post)

copy and paste the quote, add in the [ quote ] (text) [ /quote ] bracketing, and then COPY all that from the window, so you have the first quote.

If you need to cut and paste another quote from another thread... go to the reply window of that thread's quote you want. First PASTE the first quote you just copied, THEN you are free to copy the quote from the thread you are in, and add it to the same window, add the quote brackets and THEN COPY the entire window of text (which at this point has BOTH of the quotes you want. (You don't have to follow through with posting the post, just leave the page and it won't post to public.)

IF your quotes are from outside sources, use a word processor document page on your computer, or use your PM access to send yourself the quote, then after copying the next quote, FORWARD the original quoted PM to yourself, adding in the new quote. This way, you have both quotes in the same window, and can copy them altogether to take out to the forums for a complete post.

Now have I totally confused you?