Extension generates files for all pages, if was chosen only one

**Preconditions:** user installed JDN extension v.3.0.10 for Chrome Browser, user opened JDN extension in chrome dev tools on tab URLs

**Steps:**
1. Tick any checkbox
2. Click on "Generate Several Pages" button
3. Open downloaded archive

**Expected result:** there are only chosen pages as files in folder "Pages"

**Actual result:** there are three files in folder "pages"