Candlestick charts by default come with hover high,open,close,low. So when you try to replace it with custom hover text it still shows the default hover text.
library(plotly)
getSymbols("AAPL",src='yahoo')
# basic example of ohlc charts
df <- data.frame(Date=index(AAPL),coredata(AAPL))
df <- tail(df, 30)
p <- df %>%
plot_ly(x = ~Date, type="candlestick",
open = ~AAPL.Open, close = ~AAPL.Close,
high = ~AAPL.High, low = ~AAPL.Low,
text = ~paste("TEXT1:", ~AAPL.High,"<br>TEXT2: ", AAPL.Low)) %>%
layout(title = "Basic Candlestick Chart")
p

Created on 2018-10-17 by the reprex package (v0.2.1)