Stockholders of Communications Satellite Corp. have offered to sell back to the company 6.2 million shares, or 500,000 more than originaly estimated, according to revised figures released yesterday by the company.

The latest total is more than triple the 2 million shares the company announced it would buy at $37 a share in an offering that expired Tuesday night. Comsat has baout 10 million shres outstanding.

A COmsat spokesman said company officials were surprised by the number of shares tendered, but believed that a recent Federal Communications Commission order had triggered the selling interest.

During the offering period, the FCC issued an order requiring Comsat to increase significantly the funds it is placing in escrow for possible refunds to customers.

In addition, he said, Comsat shareholders may have offered more shares than usual in the expectation that the amount offered would exceed 2 millin shares and the purchases would be pro-rated.

Under the terms of the offer, Comsat willb uy all shares offered by owners of 10 or fewer shares as of Nov. 11, who tendered all such shares. After those are purchased, the company will purchase stock on a pro-rated basis.

Trading in Comsat stock was suspended Wednesday by the New York Stock Exchange as the result of the tender offer were evaluated.

Trading resumed yesterday at 1:00 p.m. when 58,400 shares were sold at $30.25, off $1.50.