Can an LLC operate under two separate business names?

I just started an online retail business in Massachusetts with which I formed an LLC - lets call it "Massachusetts Retail LLC" and it's located at massachusettsretail.com. I highly enjoyed designing my website and I'm looking to add freelancing as a service that the LLC offers. My question is: can I operate two differently named parts of the business under the same LLC? For example, Massachusetts Business would be the online retail portion located at massachusettsretail.com and Massachusetts Design Studio would be the web freelancing located at massachusettsdesignstudio.com. I imagine that I'd have to change my credit card processing account to some common name like "Massachusetts Business" so that it makes sense when collecting payments from both retail and freelancing services.

I know that the separate parts of the business wouldn't be shielded from each other, and that's fine. Working under one LLC (as opposed to setting up separate LLCs for the online retail and freelancing portions) would lessen the LLC fees ($500/year in Mass), the paperwork, and the headache. I'm also going to donate 20% of my proceeds from both aspects of the business to charities so it would make that much easier to keep track of as well.

I know that this is technically legal advice. I'm trying to save as much money as possible (hence the online-only presence). I understand that the replies to this post do not constitute legal advice nor establish an attorney-client relationship.

Thank you in advance for any responses I get!

I found this website which explains the situation quite clearly: http://smallbiztrends.com/2012/03/does-your-business-need-a-dba.html From the website:

You Need to File a DBA if...

"You have incorporated or formed a limited liability company (LLC) and are operating the business under a name that is different from the name of the company or LLC. For example, let’s say that Jane Doe Cookbooks, LLC also wants to operate under the name JanesCookbooks.com, the LLC would need to file for a DBA for JanesCookbooks.com. Likewise, if Jane Doe wanted to expand into cooking supplies, then Jane Doe Cookbooks, LLC would need to file a DBA to do business as Jane Doe Cooking Supplies."

The Benefits of a DBA...

"For an LLC or corporation, a DBA lets the company operate multiple businesses without having to create separate legal entities for each business. For example, if you plan on opening a series of websites, boutique shops, or restaurants, you might want to set up one corporation with a relatively generic name and then file a DBA for each website, shop, or restaurant. This will help you control costs and paperwork, while still expanding your business."

I'm researching the same thing (in California), and it appears that there's no reason not to. Of course, you'll have to register DBA for the "unofficial" name, but other than that it should be fine. Check with your local CPA/attorney if there's something specific for MA, but usually the LLC laws are more or less the same among the states.