Is this a BUG REPORT or FEATURE REQUEST? (choose one): BUG REPORT

Tendermint version : 0.20.0-c84be3b8

ABCI app (name for built-in, URL for self-written if it's publicly available): kvstore

Environment:

• OS (e.g. from /etc/os-release): ProductName:
  Mac OS X
  ProductVersion: 10.13.5
  BuildVersion: 17F77
• Install tools:
  git
• Others:

What happened:
I set "create_empty_blocks = false" in the "config.toml" file after "tendermint init". All except this is the default state.
In this state, I executed the command "tendermint node --proxy_app kvstore", so two blocks were created first.

1. The first block is thought of as a genesis block, and I do not know why the second block is created. (I think this is to confirm the genesis block... Is that right?)

2. Then, two blocks were created to generate the transaction. I have a transaction in one block, and I do not know why another block after it happens.

I[06-21|02:23:19.189] Block{
Header{
ChainID: test-chain-9HUwPf
Height: 3
Time: 2018-06-21 02:23:19.183178847 +0000 UTC
NumTxs: 1
TotalTxs: 1
LastBlockID: DD22E696ABC02584BB6CF5BEB16883ED76445FE2:1:F2658D478C12
LastCommit: 4069967A677C67933CB10C1D6E736D4E0EFFF41F
Data: 1EB1347A48B490C41BF131F660602F7B8E32D366
Validators: C34CF7C08DAEE6271E7FEDF4B3514D11B80835A9
App: 0000000000000000
Consensus: F66EF1DF8BA6DAC7A1ECCE40CC84E54A1CEBC6A5
Results:
Evidence:
}#0B4B6E94ADA801B1F45523BD5DD0EF2F05095CD9
Data{
Tx:Tx{616263}
}#1EB1347A48B490C41BF131F660602F7B8E32D366
Data{

}#
Commit{
BlockID: DD22E696ABC02584BB6CF5BEB16883ED76445FE2:1:F2658D478C12
Precommits: Vote{0:977FD753C2E3 2/00/2(Precommit) DD22E696ABC0 /EC1FA373554E.../ @ 2018-06-21T02:22:24.957Z}
}#4069967A677C67933CB10C1D6E736D4E0EFFF41F
}#0B4B6E94ADA801B1F45523BD5DD0EF2F05095CD9 module=consensus

Shortly after

I[06-21|02:23:20.201] Block{
Header{
ChainID: test-chain-9HUwPf
Height: 4
Time: 2018-06-21 02:23:20.190440214 +0000 UTC
NumTxs: 0
TotalTxs: 1
LastBlockID: 0B4B6E94ADA801B1F45523BD5DD0EF2F05095CD9:1:52DB4CC4AD7B
LastCommit: BD4E7B5671AD92BCDBDF38FEB8B606FB398F5EB9
Data:
Validators: C34CF7C08DAEE6271E7FEDF4B3514D11B80835A9
App: 0200000000000000
Consensus: F66EF1DF8BA6DAC7A1ECCE40CC84E54A1CEBC6A5
Results: C479B3B281039B6A3A6C9F7685A2C3948FA4DCA3
Evidence:
}#601134002FC7DBAA5B06C19A47934FBA4ACF67F9
Data{

}#
Data{

}#
Commit{
BlockID: 0B4B6E94ADA801B1F45523BD5DD0EF2F05095CD9:1:52DB4CC4AD7B
Precommits: Vote{0:977FD753C2E3 3/00/2(Precommit) 0B4B6E94ADA8 /F53697EBAC63.../ @ 2018-06-21T02:23:19.187Z}
}#BD4E7B5671AD92BCDBDF38FEB8B606FB398F5EB9
}#601134002FC7DBAA5B06C19A47934FBA4ACF67F9 module=consensus

please answer about my question.