Indel sequences have different length

[Ampholyt]

Ref and alt sequences of indels seem to have a length difference of 2 (not only indels of length two)
See in 80K MPRA: 'GC_Mendelian_variants:ALT_chr1:209816133C>CA|IRF6_chr1:209816133C>CA|IRF6',
'GC_Mendelian_variants:ALT_chr7:156791255G>C|SHH_chr7:156791274T>TTAAGGAAGTGATT|SHH',
'GC_Mendelian_variants:ALT_chr7:156791257G>A|SHH_chr7:156791274T>TTAAGGAAGTGATT|SHH',
'GC_Mendelian_variants:ALT_chr7:156791274T>TTAAGGAAGTGATT|SHH_chr7:156791274T>TTAAGGAAGTGATT|SHH',
'C_positive_heart_CAD:ALT_rs34091558_rs34091558'