Дату выдачи и дату окончания срока действия сравнили.

Because дату выдачи and дату окончания срока действия are the two direct objects of the verb сравнили (compared).

The verb сравнить takes what is being compared in the accusative:

• сравнить даты = to compare dates
• сравнить документ и копию = to compare the document and the copy

Here both nouns are singular feminine:

• nominative: дата
• accusative: дату

So:

• дату выдачи
• и дату окончания срока действия

are both accusative because both are things that were compared.

These words form a chain of of-phrases, which Russian often expresses with the genitive case instead of a separate word like of.

Breakdown:

• дата выдачи = date of issue
• дата окончания срока действия = date of expiration of the validity period

More literally:

• выдачи = of issue
• окончания = of ending / of expiration
• срока = of period / term
• действия = of validity / effect

So Russian builds this idea by stacking nouns in the genitive:

• дата
  • выдачи
• дата
  • окончания
• окончание
  • срока действия

This is very common in formal and bureaucratic Russian.

It is best understood as one unit:

• срок действия = period of validity, validity term
• окончание срока действия = the end/expiration of the validity period
• дата окончания срока действия = the date when the validity period ends, in other words, the expiration date

So although the phrase looks long, it is built step by step:

1. действие = operation/effect/validity
2. срок действия = validity period
3. окончание срока действия = end of the validity period
4. дата окончания срока действия = date of the end of the validity period

Because Russian often uses a past plural verb with no stated subject to mean something like:

• they compared
• someone compared
• people compared
• it was compared (in a loose English translation, depending on context)

This is a common way to make the sentence indefinite-personal: the action happened, but the doer is not named.

So:

• Дату выдачи и дату окончания срока действия сравнили.

literally looks like:

• They compared the issue date and the expiration date.

But in English, depending on context, you might translate it more naturally as:

• The issue date and the expiration date were compared.

Russian does this without needing to mention who did it.

Because сравнили presents the comparison as a completed action.

• сравнили = they compared / they finished comparing
• сравнивали = they were comparing / they used to compare / they compared repeatedly

In this sentence, the idea is that the comparison was carried out and completed. That is why the perfective verb сравнить is used.

This is especially natural in formal or procedural language, where Russian often reports completed steps:

• проверили = checked
• сравнили = compared
• подписали = signed

Repeating дату makes the structure clearer and more balanced.

• дату выдачи и дату окончания срока действия clearly shows that two separate dates are being compared:
  1. the issue date
  2. the expiration date

If you say:

• дату выдачи и окончания срока действия

it can still be understood, but it is denser and slightly less clear, because выдачи and окончания срока действия are both attached to the same дату. In formal Russian, repeating the noun often helps avoid ambiguity and sounds more precise.

So the repetition is not required in every context, but it is very natural here.

Yes, the word order is normal, especially in written, formal, or administrative Russian.

Russian word order is flexible. This sentence puts the two objects first and the verb last:

• Дату выдачи и дату окончания срока действия сравнили.

That can sound a bit like:

• As for the issue date and the expiration date, they compared them.

Putting the verb at the end can make the sentence feel more formal, report-like, or procedural.

A different order is also possible:

• Сравнили дату выдачи и дату окончания срока действия.

This is also correct, but the original version is perfectly natural.

Here выдача means issuance or issue in the sense of officially giving a document.

So:

• дата выдачи = date of issue
• for example, on a passport, permit, certificate, etc.

This is not the same as casual giving in everyday speech. It is a standard official word used for documents.

Срок действия is a very common fixed expression meaning:

• period of validity
• validity term
• time during which something is valid

For example:

• срок действия паспорта = the validity period of a passport
• срок действия договора = the term of a contract
• срок действия визы = the validity period of a visa

So in your sentence, дата окончания срока действия is the date when that validity period ends.

Yes. A common alternative is:

• дата истечения срока действия

This also means expiration date.

Compare:

• дата окончания срока действия
• дата истечения срока действия

Both are formal and correct.
Истечение срока действия often sounds especially standard in official language, but окончание срока действия is also perfectly normal.

It sounds formal, bureaucratic, or technical rather than conversational.

Clues:

• long noun phrases
• stacked genitives
• omitted subject
• perfective past plural reporting a completed procedure

This is the kind of Russian you might see in:

• official reports
• database descriptions
• document processing instructions
• audit/checking procedures

In casual conversation, a speaker might say something simpler, depending on context. But for official written Russian, this sentence is very natural.