وَجَدْنَا اخْتِلَافًا بَيْنَ النُّسَخِ: تَغَيَّرَ الْخَتْمُ وَنَقَصَ سَطْرٌ.
We found differences between the copies: the seal had changed and a line was missing.
Ikhtilāfan first announces a general difference. The later clauses answer the natural question 'what kind of difference?' by identifying two particulars. This illustrates clarification after an initial generality: the first expression creates a need for detail, and the second supplies it.
If only the seal mattered and the missing line were irrelevant, the expanded formulation might be less appropriate. The value of iṭnāb depends on organized disclosure of useful meaning, not on length by itself.