Shrewsbury goalkeeper Chris Weale fouled JP McGovern in the area on 68 minutes and Miller put United back on terms.
The game ended 2-2 but there was worse news for Carlisle with winger Matty Robson limping out of the game after only nine minutes with a suspected back problem
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A soggy start to the Christmas week will be slow to clear.
Continuing cloudy and mild with outbreaks of rain, heavy at times over Galloway
Cloudy with outbreaks of rain, heaviest in west