The Securities and Exchange Commission and the Internal Revenue Service are headed for a possible showdown over who gets $11.6 million in illegal insider trading profit surrendered by former investment banker Dennis B. Levine--the IRS or investors who claim to be his victims. Levine is serving two years in prison for trading on inside information and evading taxes and has given $11.6 million in assets to a receiver. But the IRS claims Levine owes more than $11 million in taxes and interest. The process for deciding who is entitled to the funds is expected to move forward today when the SEC files a distribution plan in federal court in New York which would give equal weight to claims by bilked investors and the IRS. Levine has asked the receiver to use the money to pay the IRS.