Here in Massachusetts - where it's often difficult just trying to tell the Democrats from the Republicans - this year's gubernational race has produced the most serious political identity crisis in the land.

Edward King is running for governor.

So is Edward King.

That is to say, conservative Democrat Edward J. King, the former director of the Massachusetts Port Authority and former head of the New England Council of business, and conservative Republican Edward F. King, the former director of the Massachusetts Citizens for Limited Taxation, are both running for governor.

"I'm the real Ed King," the six-foot Democrat and former pro football player tells his campaign audiences. "The other one is an impostor."

"The other Ed King has had the name 15 years longer than me so I really can't ask him to change it," the considerably shorter and more outgoing 37-year-old Republican told reporters when he announced his candidacy early last month. "But I would appoint him lieutenant governor, so that if anything happened to me we wouldn't have to change the stationery."

The two candidates' mutual dilemma has set off an exasperating string of mixed encounters, often leaving the harried voters wondering which bandwagon they were supposed to jump on.

When Edward J. King announced his candidacy in October, his Republican counterpart's aunt saw the event on television and rebuked Edward F. King for putting on weight.

One votes at a campaign stop agreed to support the Democratic King, but insisted on inspecting his business card, "Just to make sure this is the one I support."

Edward J and Edward F., both making their first bids at elective office, have been plagued with each other's mail, telephone calls - and bills.

Shortly after Edward F. King's campaign kickoff at Boston's Park Plaza Hotel, Edward J. King, who maintains campaign headquarters in the same building, received a nearly $1,000 tab.

"We're friendly," said Edward J., who refused to pay."But not that friendly."

Campaign contributions keep finding their way into the wrong King's mailbox, and there have been several instances of new campaign workers for one Ed King winding up stuffing envelopes for "the other one."

The Republican King's campaign manager, Donald Feder, tells of a potential campaign worker for the Democratic King, who, when told she had the wrong office, replied, "Well, I'm a registered Republican, so I might as well work for you instead."

In another case, Republican King campaign worker Jack O'Grady mistakenly called Edward J.'s office asking to speak to the candidate, Edward F. O'Grady told the bewildered Edward J. King he was going to drive to Fall River the next day for a campaign breakfast and set up some interviews for him. Plans were nearly finalized when they realized they were the victims of a case of mistaken identity.

"We both broke up laughing," Edward J. recalls. "And I asked him to send my regards to Edward F."

The two candidates say they could have done without some of the mistaken calls.

Edward J. relates the tale of an irate Republican who called him shortly after the Republican state party chairman, Gordon Nelson, had taken a controversial position on the party's platform.

"She just started screaming into the phone, 'Now look Ed, Gordon has just gone too far this time," the Democrat said. "That was one call I was more than happy to give to my opponent - even if I agreed with her."

And there is the case of the young Democratic campaign worker sent to pick up some campaign literature so that Edward J.'s son could drive it to his father's home. The worker, however, wound up at the wrong King's campaign headquarters.

"Well, I knew he had the wrong headquarters, because none of my kids are old enough to drive," the Republican King said. "But I couldn't resist. We piled him up with literature, but when he took a look at the picture it finally hit him that 'Gee, something's wrong here.'

The press in Massachusetts hasn't helped clear up the case of political double vision.

When Edward F. King announced recently that he was withdrawing his invitation to New Hampshire Gov. Meldrim Thomson Jr. to appear at a fund-raiser as his guest of honor, the aquiline features of Edward J. King stared out from the television tube as the story was related. An alert television news anchorman noted afterward, "Well, it wasn't the first time and it won't be the last."

Indeed it wasn't the first time. When Edward F. announced his candidacy, Edward J's picture appeared above the story, and the same sort of things has happened the other way around.

Both Kings support capital punishment and oppose gun control, busing and graduated income taxes. They are also in solid agreement in their opposition to Gov. Michael S. Dukakis, the heavily favored liberal Democrat in his bid for reelection to a second four-year term.

A statehouse wag and acknowledged supporter of "The Duke" as the governor is called, commented on the Byzantine flavor of the already preposterous political stew here.

"It's a sorry spectacle when you have two Kings ganging up on one Duke," he said.