saijeuga an majeulkka bwa gateun oseul du saijeuro jumunhaesseoyo.

In this sentence, 맞다 means to fit or to be the right size, not to be correct.

So:

• 사이즈가 맞다 = the size fits / the size is right
• 사이즈가 안 맞다 = the size doesn’t fit / the size is wrong

This is a very common use with clothes, shoes, rings, and so on.

Examples:

• 이 옷이 안 맞아요. = These clothes don’t fit.
• 신발 사이즈가 잘 맞아요. = The shoe size fits well.

So in your sentence, 사이즈가 안 맞을까 봐 means the speaker is worried the size might not fit.

-을까 봐 / -ㄹ까 봐 expresses worry, concern, or precaution about something that might happen.

Here, 맞을까 봐 literally has the idea of:

• I’m worried it might fit / might not fit
• and with 안, it becomes
• I’m worried it might not fit

So:

• 사이즈가 안 맞을까 봐 = because I was worried the size might not fit
• or more naturally, in case the size didn’t fit

A useful way to understand this pattern is:

possible bad situation + precautionary action

In this sentence:

• possible problem: 사이즈가 안 맞다
• precautionary action: 같은 옷을 두 사이즈로 주문했어요

So the speaker ordered two sizes as a precaution.

Because with 맞다 in the sense of fit, the thing that fits is normally marked as the subject, not the object.

So Korean thinks of it more like:

• The size fits
• The size doesn’t fit

That is why you often see:

• 사이즈가 맞아요
• 사이즈가 안 맞아요

not

• 사이즈를 맞아요 in this meaning

This is a common pattern for English speakers to notice, because English often frames it differently:

• The shirt fits me
• The size fits
• It doesn’t fit

Korean often uses 이/가 with what is fitting or not fitting.

The 까 here is not making the whole sentence a direct question. Instead, it adds a sense of uncertainty or wondering:

• 맞을까 = will it fit? / might it fit? / I wonder if it will fit
• 안 맞을까 = might it not fit? / I wonder if it won’t fit

When you add 봐, it becomes a fixed grammar pattern expressing concern:

• 안 맞을까 봐 = because I was worried it might not fit

So even though -ㄹ까 can appear in questions, here it is part of a grammar structure about worry or precaution, not a standalone question.

In Korean, 옷 can refer to:

• clothes in a general sense
• or a piece/item of clothing depending on context

So 같은 옷 here means the same item of clothing or the same garment/design.

In natural English, you might translate it as:

• the same clothes
• the same item
• the same outfit/item of clothing

depending on the situation.

The important idea is that the speaker ordered the same product, but in different sizes.

So 같은 옷을 두 사이즈로 주문했어요 means:

• I ordered the same item in two sizes.

두 사이즈로 means in two sizes.

The particle 로 here indicates the form, version, or way in which something is ordered.

So the idea is:

• 같은 옷을 = the same item of clothing
• 두 사이즈로 = in two sizes
• 주문했어요 = ordered

This does not mean:

• size number two
• or double size

It means the speaker ordered the same item in two different size versions, for example:

• small and medium
• M and L
• 55 and 66

So 로 is helping express the idea of as / in the form of / in these versions.

It means the speaker ordered the same item in two different sizes, so in practice that normally means two versions/items.

The emphasis is not on the number of physical pieces by itself, but on the fact that there were two sizes involved.

If the speaker wanted to emphasize simply two pieces, Korean might say something like:

• 같은 옷을 두 벌 주문했어요. = I ordered two of the same clothing item.

But:

• 두 사이즈로 specifically highlights size variation
• 두 벌 / 두 개 would highlight quantity

So this sentence is specifically about ordering multiple sizes to deal with possible fit issues.

주문하다 means to place an order, while 사다 means to buy.

So:

• 샀어요 focuses on the purchase itself
• 주문했어요 focuses on the act of ordering

This is especially natural when talking about:

• online shopping
• shopping apps
• mail order
• ordering from a store

So the sentence suggests something like:

• the speaker placed an order for two sizes
• perhaps online or through a system
• and may not even have received the clothes yet

That is why 주문했어요 is more precise here.

Because Korean very often puts the reason/background first and the main action later.

So the structure is:

• 사이즈가 안 맞을까 봐 = because I was worried the size might not fit
• 같은 옷을 두 사이즈로 주문했어요 = I ordered the same item in two sizes

This order is extremely natural in Korean. It lets the listener hear the speaker’s concern first, then the action that resulted from it.

You can think of it as:

• Because X, I did Y
• Worried about X, I did Y

That is a very common Korean sentence flow.

Yes, that is a perfectly natural translation.

As for the Korean, both ideas are possible:

• 옷이 안 맞다 = the clothes don’t fit
• 사이즈가 안 맞다 = the size doesn’t fit / the size is wrong

The sentence chooses 사이즈가 안 맞다 because it focuses specifically on the size issue, not just the clothes generally.

So the nuance is:

• not that the item itself is wrong
• but that the size selection might be wrong

That fits well with the next part:

• 두 사이즈로 주문했어요 = ordered in two sizes

So the sentence is very tightly connected around the idea of size uncertainty.