It is allowed. A buyer might get confused with following the requirements and conditions for two lenders. The lenders know right away and we are human. Lenders don't get a salary. 

The buyer can pay for 2 appraisals, it's their money but both lenders are privy to the same information and neither have any magic tricks up their sleeves. 

Only one will get paid for their efforts!

It is not legally wrong and is done frequently enough. There is still no guarantee the appraisal will be adequate.

It is not just about the appraisal but about the buyer getting the best loan.

Unfortunately, one lender will be working for nothing in the end.

It might cause a big hickup in the system because there is a central clearing office for some of this information and if multiple sources start pulling credit it may shut down the entire process.  Appraisals are getting expensive as well.  @$750.00-900.00

Anything legal is allowed if the 2 parties agree to it; that's the beauty of negotiating deals. If it's out of the norm, I always check with our in-house attorney.

Allowed? Probably.

Overkill? Yep.

Better to pick a lane.

Getting 2 appraisals hardly ensures that financing goes through.

Do the 2 lenders know about each other?

I'd imagine they would not want you wasting one of their time and energy if you are not going to use them.

Sure, if the said buyer is willing to have one lender do all the work and not get paid. Is that legally wrong in some way?  No.  

If buyers understood how much time, effort, and energy goes into processing a loan application, underwriting, and closing, would they be willing to do the same and not get paid?  I bet not. 

Yes it is allowed but is it tacky? I say yes. Decide on a lender & go with one. Think of all the duplicated effort by the loan officers & crew? Seems paranoid to me.

Belt & suspenders? Sure, they guarantee your pants won't fall down. If your point is to make sure a result takes place, there are many efficient and effective ways to accomplish that plus respecting cost too. Me? Find the pro! The master of all he/she surveys in whatever category. Pay them & relax

Dual applications is not a common thing, due to the costs involved, but it is something I've seen before.  It's either two lenders on the same loan type, or one or two lenders with different loan types.

It's a useful tactic if there are concerns about the lender's ability to perform, or if there is a concern about the property being able to qualify for a particular loan type.

The benefit is, if the one loan fails to materialize the second one is ready to go and your escrow can still close on time or with only a minor delay, versus starting a 21 day loan process all over again.

Not all lenders are equal, it would be best if you checked success rates and references and picked the right one from the start.

It is an option that few will take. Closely follow the terms of the contract.

Last year, I had a deal that had the first appraisal come in way low.  The selling agent said no way his client would go that low and my client had no way to close the appraisal gap.  The selling agent was fine with us going to a second lender and trying one more appraisal, thankfully.   The second appraisal came in at value and the deal was done.

Appraisals are not a science and the few times I have had two appraisals on a deal, they have come in about 10% different (or more).  It is expensive, but that second appraisal can work out fine.

I had never thought about two concurrently, though.  I think that would be difficult and I do not see many scenarios that I would do it.

Probably not legally wrong, depending on the language of the Purchase & Sale Contract in your State. However, at some point, only one of the Lenders will actually close the transaction and the other Lender will have spent time, money and countless hours of work on a transaction that were wasted.

WHY would a Buyer need to take such drastic steps to close on a transaction? Bad faith in one of the Lenders? more favorable terms that are only available if choosing a specific Lender? Bad Credit?

Too explore a Buyers' options on Financing is wonderful and should be done, but ahead of time and not during a transaction. Most Real Estate Agents would say that this selection of a Lender step should already be decided BEFORE making the purchase offer.

The added expense of multiple loan application fees, appraisal fees & inspection fees that  all are due and payable BEFORE underwriting approval could be a very expense option using 2 or more Lenders.

At some point, the Buyer has to choose only one Lender. Legal, maybe, ethical, not so much, cost effective, not even close.

An expensive redundancy. I would be asking questions about why? Is the borrower hiding some credit issue or truly concerned about the appraisal? Some people have more money than common sense

While you could, why would you want to? If you have serious doubts about your lender's ability to close, it would be best to change lenders and stay with only one. This is one reason most Realtors have preferred lenders that they can refer you to since they have proven track records.

This Q reminds me of those buyers who work with two or more real estate agents because they think "more is better". It's not and it is very unfair to the agents who are being used and end up working for nothing. 

Word gets around, both with lenders and Realtors, about people who play such games so if you don't trust a lender to handle the deal, discuss with your Realtor and use one of their preferred lenders.