The usual settlement proceedure in this case should be "Dead Heat" rules in which a customer would have half of his stake settled as normal, and the other half settled as a loser for each selection - unless there are more than 2 tied, in which case the stakes would be split proportionately. (1/3 stake for 3-way tie, 1/4 stake for 4 way etc).
Different books have different rules, but this is the fairest way and is the same way dead heats are settled in Golf, Horse Racing etc.
Having said that, as a one-off, we decided to pay out in full on both Kobe + Shaq - but usually, it would be settled as per the above rules. Did cost us a few k more, but not enough to worry about in the grand scheme of things!
Any book that settles this market as a "push" should be ashamed of themselves UNLESS it specifically states in their own rules that this would be the case.
Its one thing to have a poor, or uncommon, rule on your site as long as it is settled accordingly - but to have no rule in place and just decide to take the easy option is not the actions of a reputable book.
Lets face it - limits on props like this should be low enough not to drastically affect a books bottom line so why not at least pay someone out - even if it is at dead heat rules...