tidyverse - gather and spread function in R -

i have created data frame using below code:

stocks <- data.frame(time = as.date('2009-01-01') + 0:9,                    x = rnorm(50, 20, 1),                     y= rnorm(50, 20, 2),= rnorm(50, 20, 2),                       z=rnorm(50,20,4)) ) 

i have applied gather function data frame:

res<-stocks%<%gather(company, value,-time) 

while trying spread res getting error:

spread(data=res, key=company , value = value)      error: duplicate identifiers rows  

we need sequence column avoid error duplicate identifiers...

 stocks %>%      gather(company, value,-time) %>%      group_by(company) %>%       mutate(i = row_number()) %>%       spread(company, value)