The bidding war for

Data Domain

( DDUP) is heating up as

NetApp

(NTAP) - Get Report

counters

EMC's

(EMC)

offer with a $1.9 billion stock and cash bid.

The move comes less than two days after

EMC proposed a $1.8 billion all-cash offer

for Data Domain. NetApp originally bid $1.5 billion in cash and stock for Data Domain in a

prior offer

.

The square-off pits a cash-rich EMC against a less cash capable NetApp. NetApp had $1.7 billion in cash on its books and probably would have to tap the credit market to swing an all-cash deal to match EMC.

Shares of rival data de-duplication shop

CommVault

(CVLT) - Get Report

rose as much as 13% Tuesday as investors guessed that it may be the next acquisition target if NetApp fails to win the bidding war.

Data Domain makes network systems that help eliminate clutter in IT storage facilities by reducing duplications in data files. EMC and NetApp are eager to acquire the technology and get an edge in the booming storage market.

Shares of Data Domain rose 98 cents, or 2%, to $32.56 in premarket trading Wednesday.