UPDATE 2-EMC, Data Domain talked about combination

* EMC, Data Domain talked informally before NetApp deal

* Data Domain shares fall 1 percent in extended trade (Adds background on the talks)

By Anupreeta Das and Jim Finkle

NEW YORK/BOSTON, June 2 (Reuters) - EMC Corp (EMC.N) and Data Domain Inc (DDUP.O) held informal talks about a business combination several times before the smaller data storage company agreed to be bought by NetApp Inc (NTAP.O), two people familiar with the matter said on Tuesday.

The discussions concluded long before NetApp and Data Domain began the negotiations that led to their merger agreement, according to the sources who spoke anonymously because the talks were confidential.

They explored various ways that EMC, the world's top maker of data storage equipment, and Data Domain, which makes related products, could work together, said the sources.

The companies talked about partnerships, including reselling each other's products, and also about the possibility of EMC buying Data Domain, the sources said. But these talks never rose to the level of formal discussions, the sources said.

EMC has offered $30 a share in cash, or $1.8 billion, to buy Data Domain, topping a cash-and-stock offer for $1.5 billion by rival NetApp Inc that Data Domain has agreed to.

EMC made no secret of how much it covets Data Domain, which specializes in technology that allows customers to get rid of duplicate, or redundant, data, freeing up costly storage space in computers.