The news sent Data Domain shares rose 2.7 percent to $34.10 in premarket trade, suggesting that investors expect the two companies to bid up the price even higher.
Both suitors also said that they had won U.S. antitrust approval to pursue their purchases of Data Domain, whose sales are growing far faster then either EMC or NetApp.
Investors had closely watched that process because if regulators had delayed either bid, the other would have had a clear advantage with shareholders eager to quickly close a sale.
Data Domain's board said that NetApp's $30-per-share cash-and-stock offer was superior to an all-cash offer from EMC, citing a breakup fee and other deal protections in EMC's proposal. But the higher offer will force directors to reconsider their decision.
EMC Chief Joseph Tucci sweetened his proposal further by removing the break-up fee and other deal protections in the revised offer that he presented in a letter to Data Domain Chairman Aneel Bhusri on Monday.
A spokesman for NetApp declined comment on the revised EMC bid.
(Reporting by Jim Finkle; Editing by Derek Caney)