Rep. Barbara Mikulski (D-Md.) raised substantially less money for her Senate race than was stated on the campaign finance report filed last Friday because of "an inadvertent bookkeeping error," according to campaign treasurer Neil J. Schechter.

A Mikulski spokesman said later that an amended campaign report would be filed today with the Federal Election Commission.

The FEC report filed Friday showed Mikulski the front-runner in fund raising for the Maryland race for the U.S. Senate, when, in fact, she lagged far behind Rep. Michael D. Barnes (D-Md.), according to the new figures.

In the Friday report, Mikulski said that she had raised $197,098 in 1985 and had transferred $132,334 from her House campaign committee, for total 1985 receipts of $329,432.

Actually, Mikulski's total receipts last year were closer to $184,000, with $51,307 raised for the Senate race and the rest transferred from her House campaign, according to Schechter. Barnes raised $173,099 and had total receipts of $349,950.

Schechter said the mistake occurred because much of the $132,334 transferred from her House campaign committee had been mistakenly counted twice. The $197,098 figure included money raised for the Senate and House in 1985, although House campaign funds also were included in the money transferred from other campaigns