mass cannot be matched

[YoujiaMa]

hi pyAscore team. I have a problem that my mass spectrometry data had two modifications to K, and when I submitted the code, the following example spectral data data seemed to be wrong. , and two K modifications become the same.

## input code
pyascore.IdentificationParser(psm_file, "pepXML")

###  pepXML infomation
<aminoacid_modification aminoacid="K" massdiff="42.010565" mass="170.105528446600005" variable="Y" binary="N" description="Acetyl (K)"/>
<aminoacid_modification aminoacid="C" massdiff="57.021464000000002" mass="160.030648985200003" variable="Y" binary="N" description="Carbamidomethyl (C)"/>
<aminoacid_modification aminoacid="K" massdiff="43.005814000000001" mass="171.100777414700019" variable="Y" binary="N" description="Carbamyl (K)"/>
....
<spectrum_query spectrum="01CPTAC_UCEC_A_PNNL_20180621_B1S1_f03.3256.3256.2" start_scan="3256" end_scan="3256" precursor_neutral_mass="1155.692700233000096" assumed_charge="2" index="3255" retention_time_sec="638.6" >
<search_result>
	<search_hit hit_rank="1" peptide="KKSLNPR" peptide_prev_aa="R" peptide_next_aa="R" protein="DECOY_sp|Q5TCZ1|SPD2A_HUMAN" num_tot_proteins="1" num_matched_ions="0" tot_num_ions="0" calc_neutral_pep_mass="1155.692700233000096" massdiff="0.0" num_tol_term="1" num_missed_cleavages="0" is_rejected="0" protein_descr="Protein No. 1">
		<modification_info modified_peptide="n[230]K[171]K[170]SLNPR" mod_nterm_mass="230.170757031900024">
			<mod_aminoacid_mass position="1" mass="171.100777414700019"/>
			<mod_aminoacid_mass position="2" mass="170.105528446599976"/>
		</modification_info>
		<search_score name="Posterior Error Probability" value="0.711939"/>
		<search_score name="Posterior Error Probability" value="0.711939"/>
		<analysis_result analysis="peptideprophet">
			<peptideprophet_result probability="0.288061" all_ntt_prob="(0.0000,0.0000,0.288061)"/>
		</analysis_result>
	</search_hit>
</search_result>
</spectrum_query>
...


## ouput data
scan	charge_state	score	peptide	mod_positions	mod_masses
....
3256	2		KKSLNPR	[0 0 2]	[230.17076111  42.010565    42.01056677]
....