I struggle to make one cleric do her share of the work, so I'm not sure how well two would work. Your party could have two summons up at once, which would be nice, and if one or both take scribe scroll you'd have access to a wider range of spells thanks to spell sharing (e.g. have one as a dedicated healer taking healing spells and scribe scroll, the other can take offensive spells but NOT scribe scroll and still have the healing spells for backup/fighting undead).
I think Void is right in that a Knight would be a better choice if you want a pure ranged damage character, simply because of the number of feats involved: Point Blank Shot, (Improved) Precise Shot, Dodge, Mobility and Spring Attack are all useful, and then a weapon focus on top of that. A cleric won't be able to use bows either, so you'd also want either a bow proficiency or rapid reload.
If you go for an offensive caster, you'll probably want (Greater) Spell Focus(Necromancy) and maybe (Greater) Weapon Focus(Touch) since a lot of the cleric's single target damage/kill spells are touch attacks. (Greater) Spell Penetration is very important, along with Superior Concentration so your melee touch attacks don't fail. You could also consider Spell Focus(Conjuration) since it covers your healing spells (for when you're fighting undead) and is a prerequisite for Augment Summoning, but I'm not sure if it's worth it. Wis then Con would be your most important stats, followed by Dex and/or Str: Weapon Finesse works for melee touch attacks so you could almost ignore Str completely if you took it (although I've already suggested more feats than a cleric gets). Still (since you'll be at risk of grapples) and Heighten/Maximise/Empower (to get the most out of your single target spells in the late game) are metamagics worth considering. While the cleric's 'inflict' damage spells have lower dice than equivalent level wizard spells, they deal negative energy damage which only undead and constructs have immunity to.
Now that I've thought about it this does sound like an interesting build - might make a cleric like this in my next game
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