Let's call one of your URLs "OJ" and the other "water."
You put two in, now your orange juice is only HALF as juicy as it was before. And the power of your brand, "OJ," is FIFTY PERCENT diluted.
And you may think it's tasty, but that's only HALF the vitamins of undiluted orange juice.
(Said in Plain English):
For those who run multiple websites:
How do you choose which URL to place in your article resource box?
As a marketing-minded individual, I choose the URL that's most appropriate for the audience.
For example, If I'm selling, say, orange juice, and my one site is "Freshpicked.com" but the other is called "dreamingincolor.com"... guess what?
I'm not including that second URL in the resource box... no matter how much I want everyone to notice how many websites I'm running.
I notice that many people include more than one URL in their article resource box, and I advocate strongly against it.
Even if the reader "knows you from around the internet," you are not attracting people to one website if you give them two options of where to click.
If you give ONE option, and someone clicks, they can explore the potentially many pages of one website, and let the info sink in and then burn your name into your head.
If you give them two, you've diluted the power of your brand by FIFTY PERCENT.
Do you think this helps to build a strong case for your brand? I don't.
People are NOT going to click TWICE.
They're just not, so don't give them a distraction with your two-URL-having resource box.