I don't know if there are local modifications to the NEC that would prohibit your installation, but in general, there's no limit to the number of receptacles in a box. There are box-fill calculations to contend with, but in your installation with only one cable entering the box, box fill won't be an issue.

Ask your local hardware store guy for a reference in the NEC (or local addendums) that disallows your configuration.

"He said that it does not meet code to have more than one receptacle in a 3-gang box. "

unless there is a local change to the NEC he is full of bovine scatology.

The selection of triple switch-plates for a triple receptacle is smaller than a single or double, but that is the only real issue.

The local hardware guy is a moron

sbrn33 wrote: "The local hardware guy is a moron"

IMHO, you overrate both his knowledge and his intelligence.

What I want to know is where do these clowns come up with these made up codes.

"What I want to know is where do these clowns come up with these made up codes."

Code?

he has probably never actual touched a code book,let alone read and understood it.

At least he is not an AHJ with fantasy requirements

Thanks for your input. I can't explain it. While I was waiting for replies I was able to talk to 2 electricians here in town and they both thought that I had to put the receptacles in separate boxes, just like the Home Depot guy. So then I really started searching for an answer and the next two electricians I talked to said there is no problem. The one thing everyone agreed on is that even in one gang box it should be perfectly safe. I have no idea why so many seemingly competent professionals can't agree on something like this, which can't be nearly as exotic as it's being made out to be. I mean, I see quad boxes everywhere.

Let's back up a second. Are you talking about a bathroom circuit with a 15 amp GFCI outlet? If so, then your current plan doesn't quite cut it. The bathroom should be on a 20 amp circuit even if it has a 15 amp gfci outlet. You need to continue using 12-2, not 14-2, to run between outlets even if those outlets are in the same box. Wire sizing is dictated by the breaker rating, not the outlet rating.

If this circuit really is on a 15 amp breaker, modifying part of it means you'll need to bring the whole thing up to code - eg completely rewiring the bathroom with 12-2 and a 20 amp breaker.

I won't be able to double check until tomorrow, but yes, it looked like it is on a 15A circuit, nothing about it made me think it was on a 20A circuit, it's on 14-2 wire (consistent with being on a 15A circuit), and it is in a bathroom, just powering a clock radio and an electric toothbrush when we don't temporarily plug in a razor or some hair trimmers.

This circuit powers this bathroom's 15A GFCI, and then the line side continues to power some outlets in another room. (I realize that those outlets in the other room are not protected by the GFCI since they're coming off the line side instead of the load side.)

So are you saying that all bathrooms MUST be on a 20A circuit? If that's true, it makes me wonder if the old home owner added this line himself and didn't know or care. I just added the two receptacles to the existing GFCI that was already there on 14-2 wire on a 15A circuit. But I'll double check tomorrow. Hopefully, if anything, it is actually on a 20A and 12-2, then I can just switch out my new wires. I just can't see how I would not have noticed that.

"So are you saying that all bathrooms MUST be on a 20A circuit?"

The 20 amp bathroom circuits has been around for many years know.
A receptacle ,ust be adjacnt tothesink \, GFCI protected, an o a 20 amp circuit.

There are some exceptions that allow a single 20 amp circuit to fed multiple bathrooms, if it does not feed anything else (like bathroom lights) but is restricted to the basn outlets..

It it serves a single bathroom other bathroom outlets can be on the circuit (like bathroom lights and fans), but ONLY in a single bathroom.

With GFCI receptacles being less than $15 most folks choose to use a separate 20 amp circuits per bathroom.
it also helps if you need to run more than onw blow dryer at a time.

They use up a large portion of a 20 amp circuit (often 11-12 amps, and sometimes more).

Blow dryer makers like to play games with the power rating of the dryers, like calling out a power based on 130 V instead of 120 V. It makes them sound more powerful tan they actually are.

"So are you saying that all bathrooms MUST be on a 20A circuit?"

Yes, the bathroom needs it own 20amp circuit and it can't be shared with the bedroom. Depending on how old the house is, that may or may not have been a requirement when the prior work was done.