In the equation \(\frac{x(x - 1) - (m + 1)}{(x - 1)(m - 1)} = \frac{x}{m}\), find the value of \(m\) such that the roots are equal. The original answer is in the form \(-\frac{a}{b}\). Please provide the value of \(a + b\).

Let's think step by step and output the final answer within \boxed{}.
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