Mdthbs

For many words, the dative and ablative take the same form. Two examples are nos and vos (nobis and vobis, respectively).

Imagine you want to say something like "from us to you [plural]" (where "from" indicates ablative and "to" dative). Since the order is usually uninformative in Latin, nobis vobis is not precise enough. Would something like a nobis vobis be enough?

Similarly, say you want to say "from us to us". Is nobis nobis enough, or would a nobis nobis be more accurate?

More generally, how would one disambiguate these cases where dative and ablative go together? Is it making one of the prepositions explicit, as above?

Let me make some remarks on what you say above: "Imagine you want to say something like "from us to you [plural]" (where "from" indicates ablative and "to" dative). Since the order is usually uninformative in Latin, nobis vobis is not precise enough. Would something like a nobis vobis be enough?".

As pointed out by Joonas, context is important here. For example, if the verb dare is involved, the example from Plautus given by brianpck is indeed very natural. If the verb is transire, the most adequate construction would be another one: e.g., cf. August. Bapt. 1.10.13: qui transeunt a nobis ad vos.

Finally, please let me make a more general remark on what you say above: "the order is usually uninformative in Latin". This is often said in some (traditional) Latin grammars but it is not correct. Quite the opposite! Despite appearances, word order is usually informative in Latin. For those of you who are interested in word order in Latin, three important recent works are:

Devine, Andrew M. & Laurence D. Stephens (2006). Latin Word Order. Structured Meaning and Information. New York: Oxford University Press.

Devine, Andrew M. & Laurence D. Stephens (2019). Pragmatics for Latin. From Syntax to Information Structure. New York: Oxford University Press.

Spevak, Olga (2010). Constituent Order in Classical Latin Prose. Amsterdam/Philadelphia: John Benjamins.

I agree with the other answers: though ambiguity sometimes is inevitable, the ablative wouldn't be used alone in this context. Here is an example from Plautus that almost exactly parallels your case (with some previous lines added for context):

Gel. [...] Quid igitur me volt?

Croc. Tritici modios decem rogare, opinor [te volt].

Gel. Mene, ut ab sese petam?

Croc. Immo ut a vobis mutuom nobis dares. (Stichus, I.3)

My translation:

Gel. So what does she want me for?

Croc. I think she wants you to ask for ten pecks of wheat.

Gel. She wants me to ask her for it?

Corc. No, she wants you to give a loan, from you to us.

Despite its name, the Latin “ablative” is not normally used on its own for motion from a place or person. (Often, as in nobis and vobis, the “ablative” is historically not an ablative at all, but an old instrumental). I would stick with “a nobis vobis”.

Ambiguity like this is commonplace in Latin.
For example, "we have to help you" can be nobis vobis auxiliandum est, where the two datives happily mix the two roles.
(In this specific case one of the datives can be replaced by an agent a nobis, but sometimes ambiguity is inevitable.)

Even though Latin word order is flexible, it does contain information.
Especially with ambiguities word order can suggest what is meant.

Your suggestions a nobis vobis and a nobis nobis work fine.
In the second case I might add an ipsis for clarity.
This would only clarify that the same party plays both roles and the repetition of the pronoun is no accident.
If you really want to disambiguate the two roles, something more elaborate is needed.

In general, if you end up with something ambiguity and want to disambiguate, I suggest trying to restructure the entire thought.
Maybe switching between active and passive helps.
Maybe you can turn a personal verb into an absolute ablative.
Maybe you can put the ambiguous entities in two separate sentences.
I have no general magic tool; it all depends on context.