Washington CNN  — 

Hillary Clinton emailed her staff with multiple devices while serving as secretary of state, according to a source with knowledge of the emails, a revelation that raises questions about a main defense Clinton has used in her email controversy.

Clinton used an iPad and a Blackberry for email, the source said Tuesday, confirming an Associated Press report that Clinton emailed with staff about both work and personal issues on her iPad.

Clinton’s exclusive use of a personal email account and server while at State has grown into a controversy that has defined the run up to Clinton’s expected April presidential announcement. In a press conference at the United Nations earlier this month, Clinton explained that she used a personal email because she only wanted to have one phone, not two.

“When I got to work as secretary of state, I opted for convenience to use my personal email account, which was allowed by the State Department,” Clinton said, “because I thought it would be easier to carry just one device for my work and for my personal emails instead of two.”

She added: “Looking back, it would’ve been better if I’d simply used a second email account and carried a second phone, but at the time, this didn’t seem like an issue.”

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That clearly changed, however, once the Apple released the iPad in 2010, a year after Clinton took over at State.

Republicans pounced on the AP revelation on Tuesday. The RNC blasted the story to reporters, arguing it that Clinton “was not being truthful when she claimed to have built her secret server for the ‘convenience’ of using one device.”

A source close to Clinton, however, argued on Tuesday that “the AP reporting on her iPad use later on during her time at State does not contradict her UN comments at all.”

“She said her reason for opting for one email account in 2009 was a desire to not have to carry more than one device around,” the source said. “And in the second sentence of the above statement, she specifies that the extra device she was seeking to avoid was ‘a second phone.’”

The AP released four emails from Clinton that were unclassified by the U.S. Department of State. Among those emails were an exchange between Clinton and Huma Abedin, her longtime aide and confidant, that blended work and personal topics.

On September 18, 2011, Abedin forwarded Clinton an AP story about a drone crash along the Afghan border. Inadvertently, Clinton responded with an email about decorations.

“I like the idea of these,” Clinton wrote. “How high are they? What would the bench be made of? And I’d prefer two shelves or attractive boxes/baskets/containers [sic] on one. What do you think?”

Abedin responded asking, “Did u mean to send to me?”

“No - sorry!,” Clinton wrote back. “Also, pls let me know if you got a reply from my ipad. I’m not sure replies go thru.”

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The exchange was part of the over 55,000 pages of emails that Clinton turned over to the State Department in December. Clinton has asked that those roughly 30,000 emails be released to the public. State Department officials have said they will release them after they have been reviewed, a process that could take months.

During her United Nations press conference, Clinton argued that her team went “above and beyond” in providing the State Department with any emails related to work. The exchange with Abedin appears to buttress that defense – the email included personal exchanges but Clinton’s team turned it over to State anyway because it also addressed a work issue.

Other emails in the AP release include Clinton emailing with top aides about a CNN story on Obama administration national security. “I think this is both dishonorable and dangerous and want to find way to say it,” Clinton wrote in response to the piece.

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Clinton’s iPad revelation comes the same day that Trey Gowdy, Chairman of the House Select Committee on Benghazi, sent a letter to Clinton’s lawyer requesting that the former secretary of state appear before the panel for a transcribed interview on her email usage.

“This Committee is left with no alternative but to request Secretary Clinton appear before this Committee for a transcribed interview to better understand decisions the Secretary made relevant to the creation, maintenance, retention, and ultimately deletion of public records,” Gowdy said in a letter to David E. Kendall. “The Committee is willing to schedule the interview at a time convenient for Secretary Clinton, but no later than May 1, 2015.”

Gowdy also said that if Clinton “continues to reject the offer of a neutral review, the House of Representatives as a whole will need to consider its next steps.”

The chairman subpoenaed Clinton’s emails regarding Libya and, last month, the State Department turned over about 300 emails to the committee.

Gowdy said in his letter that once there is a “reasonable assurance” that Clinton had control of her documents, the panel could “schedule her appearance in a public hearing to constructively discuss these topics.”

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CNN’s Chris Frates contributed to this report.