i du madaeneun ttokgatseupnida.

Korean also puts both the demonstrative and the number before the noun.

• 이 = this / these
• 두 = two
• 마대 = sack

So 이 두 마대 literally lines up as this two sack(s), but in natural English it means these two sacks.

A very common Korean pattern is:

demonstrative + number + noun

So:

• 이 두 마대 = these two sacks
• 그 세 사람 = those three people
• 저 네 건물 = those four buildings over there

둘 is the basic form of two, but before a noun it usually changes to 두.

So:

• 둘 = two
• 두 마대 = two sacks

This happens with some native Korean numbers:

• 하나 → 한
• 둘 → 두
• 셋 → 세
• 넷 → 네

Examples:

• 한 사람 = one person
• 두 마대 = two sacks
• 세 개 = three things
• 네 명 = four people

So 둘 마대 would sound wrong here.

Because 두 already tells you there are two of them.

In Korean, nouns often do not need a plural marker when the number is already clear. So:

• 두 마대 = two sacks
• not necessarily 두 마대들

Using 들 here would usually sound unnecessary or unnatural.

Korean often leaves plurality unmarked when context, a number, or another word already makes it obvious.

는 is the topic particle.

It marks 이 두 마대 as the thing the sentence is talking about:
As for these two sacks, they are identical.

So 이 두 마대는 똑같습니다 has a feeling like:

• Speaking of these two sacks, they are the same
• These two sacks, as for them, are identical

This is very natural when you are comparing them with something else or simply making them the topic of discussion.

Yes, 이 두 마대가 똑같습니다 is also possible, but the nuance changes a little.

Very roughly:

• 는 = topic, sometimes contrastive
• 가 = subject, often more neutral or more focused

So:

• 이 두 마대는 똑같습니다
  = As for these two sacks, they are identical
• 이 두 마대가 똑같습니다
  = These two sacks are the ones that are identical or simply a more subject-focused statement

In many everyday situations, both are possible. But 는 is especially common if you are comparing these sacks with others.

Korean does not need a separate word like English are in this sentence.

The word 똑같습니다 already works as the predicate of the sentence. It means is/are identical in a polite formal way.

So Korean can say:

• 이 두 마대는 똑같습니다

without adding anything equivalent to English are.

This is normal in Korean. Descriptive words such as 크다 (to be big), 작다 (to be small), 같다 (to be same/alike), and 똑같다 (to be exactly the same) function as predicates by themselves.

똑같습니다 is stronger.

• 같습니다 = are the same / are alike / are similar
• 똑같습니다 = are exactly the same / are identical

So 똑같다 emphasizes that there is basically no difference.

If you just want to say two things are similar or the same in a looser sense, 같다 may be enough. If you want exactly the same, 똑같다 is a very natural choice.

-습니다 is a formal polite sentence ending.

So 똑같습니다 is the formal polite form of 똑같다.

This style is common in:

• formal speech
• presentations
• announcements
• customer service
• writing with a formal tone

Other possible levels would be:

• 똑같아요 = polite, less formal
• 똑같아 = casual

So the sentence could also appear as:

• 이 두 마대는 똑같아요.
• 이 두 마대는 똑같아.

depending on the situation.

That is a very reasonable question, because Korean often uses counters when counting nouns.

In this sentence, 두 마대 is acceptable because 마대 itself is being treated as a countable item: two sacks.

You may also hear structures with a counter in other contexts, and Korean counting can vary depending on the noun and style. But 이 두 마대 is a natural way to say these two sacks.

So the important point for a learner is:

• not every counted noun must appear in exactly the same pattern
• 두 마대 is a normal expression here

In careful standard pronunciation, it is often heard roughly like 똑깓씀니다.

That is because Korean pronunciation changes can happen when sounds meet across syllables and endings.

So even though it is spelled:

• 똑같습니다

you may hear something closer to:

• 똑깓씀니다

This kind of sound change is very common in Korean, especially with -습니다 endings. It is worth learning both the spelling and the actual spoken sound.