Gdtyjr

I'm trying to cite two different papers that share the same author and were publicated the same year. Here is an example:

documentclassarticle

usepackage[ backend=biber,
 style=authoryear,
 sorting=nyt,
 useprefix=true, 
 sortlocale=de_DE,
 natbib=true,
 doi=false,
 isbn=false,
 maxcitenames=2, 
 maxbibnames=99,
 eprint=false]
 biblatex
usepackagefilecontents

beginfilecontents*general.bib
@articlegiacometti16a,
author = "Giacometti, R. and Zavala, J.A. and Gog, L.",
year = 2016,
pages = 68-77,
title = Anthropogenic increase in carbon dioxide modifies plant–insect interactions,
journal = Annals of Applied Biology,
volume=170,
number=1,
doi = 10.1111/aab.12319

@articlegiacometti16b,
author = "Giacometti, R. and Barneto, J. and Barriga, L. G and Sardoy, P.M. and Balestrasse, K. and Andrade, A.M and Pagano, E.A and Alemano, S.G and Zavala, J.A.",
title = Early perception of stink bug damage in developing seeds of field-grown soybean induces chemical defences and reduces bug attack,
journal = Pest Management Science,
volume = 72,
number = 8,
pages = 1585-1594,
keywords = herbivory, jasmonic acid, MAPK signalling, plant–insect interactions, salicylic acid, Glycine max L, Nezara viridula L,
doi = 10.1002/ps.4192,
url = https://onlinelibrary.wiley.com/doi/abs/10.1002/ps.4192,
eprint = https://onlinelibrary.wiley.com/doi/pdf/10.1002/ps.4192,
year = 2016

@articlethomma01,
title = "The complexity of disease signaling in Arabidopsis",
journal = "Current Opinion in Immunology",
volume = "13",
number = "1",
pages = "63 - 68",
year = "2001",
issn = "0952-7915",
doi = "https://doi.org/10.1016/S0952-7915(00)00183-7",
url = "http://www.sciencedirect.com/science/article/pii/S0952791500001837",
author = "Thomma, B.P and Penninckx, I.A. and Cammue, C.P. and Broekaert, W.F.",
keywords = "Arabidopsis thaliana, salicylic acid, jasmonic acid, ethylene, biotroph, necrotroph",
abstract = "Not more than 10 years ago it was generally accepted that pathogen-inducible defense mechanisms in plants are triggered through a central signaling cascade that regulates a multicomponent defense response. Now we know that the plant defense system is regulated through a complex network of various signaling cascades."

endfilecontents*

addbibresourcegeneral.bib

nocite*

begindocument

As is saying in parencitegiacometti16a, parencitegiacometti16b and in parencitethomma01

printbibliography

enddocument

And this is how latex make my pdf:

As you may noticed when two paper share the same author and year, biblatex cite the first and second author (Giacomettis´s references)
But I don't want differentiate this twins references beeing differentiated on that way, I want only the first author to be cited and then the year with a letter "a" for the first paper and with a letter "b" fot the second paper. Here is an example:

Does anyone knows how can I fix this issue?

Thanks!!