Several weeks ago we told you that Garth Brooks would be among the stars participating in Equality Rocks, a concert being billed as the largest such event benefiting gay and lesbian concerns. Now, it has been reported that Brooks and George Michael will perform a duet of Michael's hit "Freedom" during the festivities. The concert at RFK Stadium in Washington, D.C., is scheduled for April 29, the night before a gay and lesbian march in Washington that is expected to draw one million people. The concert will benefit the Human Rights Campaign, which lobbies Congress for legislation fair to gays and lesbians. Melissa Etheridge, k.d. lang, Queen Latifah, the Pet Shop Boys and Ellen DeGeneres are also on the bill.