I now take nesting tubes that can splint an upper, a lower, or a tent pole. (I tightly wrap a skein of 2mm "emergency cord" and stuff it inside to utilize that volume.)
You can find thinwall brass tubing at most hardware stores, or at Michael's, in sizes to closely fit over both the uppers and the lowers. Clean up the shattered ends, slide the tubing over and tape it in place.
If an end is effectively destroyed/split for a number of inches I would suggest cutting back until you get to solid material. Otherwise one end could split around the other and then telescope in.
I used this technique on a recent trip and pole held up well for the remaining 5 days.