Lehman Brothers is seeking court permission to probe whether its US brokerage unit was undervalued when it was acquired by Barclays last year.In documents filed in the US Bankruptcy Court in Manhattan, Lehman said it "has become aware of apparent material discrepancies relating to the liabilities Barclays was to assume.""In the aggregate, these apparent discrepancies may have resulted in a windfall to Barclays at the expense of the estate, its creditors and other parties in interest, in an amount that could reach into the billions of dollar," according to the papers. Barclays paid $1.75bn for the business just days after Lehman's bankruptcy filing last September.