The Democratic Congressional Campaign Committee, in a new, more combative mood, has begun copying tactics leanred from its rival Republican committee. But at least one detail apparently wasn't copied closely enough to avoid complaints.

A "press release" sent out by the Democratic committee has been characterized as a "dirty trick" by Robert Siegrist, press officer for Rep. E. G. (Bud) Shuster (R-Pa.).

The release, attacking Shuster for voting against impact aid for his district, was sent to media in Shuster's district last week. It was one of mnay sent out during the past two months to the home media of Republican congressmen, attacking them ferociously on different issues.

The relases read "Congressional News Service" in large type across the top, with the name Evan Zeppos underneath. Siegrist said that might lead one to believe it came from an "authentic, accredited news organization." Siegrist also said the one attacking Shuster was unsigned and written entirely in unattributed language.

At first Siegrist had seen only a poorly copied version of the release and thought the source of the release, the Democratic campaign committee, was not named in the release.

Later, Siegrist found out that the Democratic committee is named in the press releases, in extremely fine type at the bottom of the page, which apparently was obscured in Siegrist's photocopy.

The fine type doesn't change things, Siegrist said; the release still looks as if it is coming from a legitimate news service.

"He's entitled to his opinion," said Evan Zeppos, the press staffer for the Democratic campaign committee and the man who put out the Shuster press release. "The Democratic committee is mentioned on there. Any good newsman can see that. And my name and phone number are there."

"We are doing the best damn job of copying the Republicans we can," said Martin Franks, staff chief of the Democratic campaign committee. He said that the Democrats, in playing the role of party-out-of-power, are using mailed newsletters to attack Republicans in their home districts and will be targeting GOP leaders and committee chairman for special attacks in the coming election.

The Republicans came up with the idea of press releases sent into the home districts of the opposition to try to stir up negative reports. Theirs was called "News from the other side" and displayed the name of the Republican campaign committee prominently at the top of the release. It was also preceded by a letter to editors, explaining the release program, said a Republican staff leader at the campaign committee.

It's said that imitation is the sincerest form of flattery, and the Republican staffer said "we're flattered," but added, "I think those tactics are out of date now."