Pour peu que nous trouvions un doublon, vérifions tout.

It is an idiomatic conjunction, not something you should translate word by word.

Here, pour peu que means something like:

• if
• provided that
• if it happens that
• all it takes is for...

Very often, it carries the idea that even a small thing is enough to trigger the result.

So in this sentence, the nuance is close to:

• if we find even one duplicate, let's check everything
• the moment we find a duplicate, let's check everything

It is a bit more nuanced and often a bit more formal or literary than a simple si.

Because pour peu que normally requires the subjunctive.

So:

• pour peu que nous trouvions = correct
• pour peu que nous trouvons = not standard

This is one of those fixed expressions that trigger the subjunctive, just like:

• bien que
• afin que
• pour que
• à moins que

So the sentence uses trouvions because French treats the action as a condition rather than a straightforward fact.

Yes, here it is definitely the present subjunctive.

For many -er verbs, the nous and vous forms of the present subjunctive look exactly like the imperfect indicative:

• nous trouvions
• vous trouviez

So the form by itself is ambiguous, but the grammar around it makes the meaning clear.

Because the sentence has pour peu que, the form must be understood as subjunctive, not imperfect.

It is the first-person plural imperative of vérifier.

So vérifions means:

• let's check
• let us verify

This is the French way to give a suggestion, instruction, or command that includes the speaker.

Compare:

• Nous vérifions tout. = We are checking everything / We check everything.
• Vérifions tout. = Let's check everything.

The missing subject pronoun nous is a strong clue that this is the imperative.

Because French imperatives normally drop the subject pronoun.

So:

• Vérifie ! = Check!
• Vérifions ! = Let's check!
• Vérifiez ! = Check! or Check, please!

If you say nous vérifions, that is no longer an imperative. It just means we check or we are checking.

So vérifions is the proper form for a suggestion or decision involving we.

Un doublon usually means a duplicate, especially in practical contexts such as:

• databases
• spreadsheets
• paperwork
• records
• lists
• inventory

So it often means a duplicate entry or duplicate record, not just any kind of general doubleness.

For example:

• Il y a un doublon dans la base de données. = There is a duplicate entry in the database.

In your sentence, un doublon most naturally suggests one duplicate item/record.

Because tout here means everything.

• vérifier tout = to check everything

By contrast, tous is usually used before a plural noun or as a plural pronoun:

• vérifier tous les fichiers = check all the files
• ils sont tous là = they are all there

So:

• tout = everything / the whole thing
• tous = all of them / all the plural items

In this sentence, the idea is not all duplicates, but everything overall.

Yes, in many situations you could say:

• Si nous trouvons un doublon, vérifions tout.

That is more neutral and straightforward.

The difference is nuance:

• si = simple if
• pour peu que = if even that small condition is met, all it takes is...

So pour peu que adds a sense that finding a duplicate is enough, by itself, to justify checking everything.

Yes, it is understandable and grammatically fine, but pour peu que sounds a bit more formal, written, or deliberate than everyday casual speech.

In ordinary spoken French, people might more often say something like:

• Si on trouve un doublon, on vérifie tout.
• Si nous trouvons un doublon, vérifions tout.
• Au moindre doublon, on vérifie tout.

So the original sentence is natural enough, but not the most casual everyday phrasing.

The comma separates:

• the conditional clause: Pour peu que nous trouvions un doublon
• the main clause: vérifions tout

This is very common in both French and English when a condition comes first.

So the structure is:

• If X, then Y
• Pour peu que X, Y

The comma helps the sentence read clearly and marks the shift from the condition to the action to take.

Not really in a way you need to translate separately here.

Pour peu que functions as a fixed expression. You should learn it as a whole, just like you learn:

• bien que
• afin que
• pour que

So while que is part of the conjunction grammatically, the important thing for a learner is to recognize pour peu que as one unit meaning something like if only / provided that / if it happens that even slightly.