You can’t directly use a display object as two different inputs to a filter. You could potentially use a snapshot object to render a display object into it, then apply a filter, save that, apply a filter etc… However, based on what I think you are interested in doing it may be similar to what we do in the bloom filter for example, which is in itself a multipass shader, it applies a levels pass filter, a blur filter, and combines the two together using the composite filter.
