Never seen one, either put it horizontally if enough slack in excisting and form both into a 90 before entering block(not tight up against it, you want a few inches after the bend before the block) or put it in vertically with the existing in top and bottom and pick one end for the new and dress it round in a neat bend.
Remember to remove about 6-8mm more of the grey sheath than the inner insulation so it sort of forms a cone when terminated, and you should have none of the inner insulation visible when done and absolutly no way you can sneak a test probe onto live copper by forcing it between the block and the grey sheath (as might happen if they were cut to the same length). Sorry to state the obvious, but I see so many blocks made of by suposedly skilled folk that have these issues.
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